Collards.

You keep eating the lower leaves and the plant keeps growing until it finally goes to seed.

Has anyone grown chayote? Is it too late to plant it?

Okra, if you like it! It is expensive at the greengrocer, but grows easily, no maintenance other than picking promptly. We toss slices in cornmeal and "fry" in a dab of oil on a non-stick pan. Crunchy and nutritious.

Spaghetti squash is another pricey one at the store that grows easily. Interestingly, I have only had success with saved seed from grocery store squashes. Whenever I buy seed, the plants don't make it.

And, of course, leaf lettuce. The nicer lettuces are expensive at the grocery. A little more labor intensive than the zucchini, though.

Chard is a great suggestion. The red ones even look nice in the flower garden or shrub border.

Tomatoes!

Since its close to impossible to buy a really good tomato at any price planting tomatoes gives you something that no money can buy.

White patty pan squash are nearly as unobtainable so they're a must as well.

With the current price of cukes and peppers in the grocery store I'll only need to pick a dozen or so to pay for the seed/plants.

Having limited space, I don't grow space hogs that I can readily buy fresh or frozen for low prices -- broccoli, potatoes, onions, cabbage, etc.

I grow collards now that I'm living in the south. They're amazing. I do yankee collards -- sauteed in olive oil with garlic and balsamic vinegar. When I first moved south I didn't know how to cook them so I adapted my Italian-derived recipe for kale.

I do grow beans, but only the purple and yellow ones.

potatoes are great - you get a lot of calories out of a small space.

We grow hops on a couple of trellis - no significant flower, but they grow fast and provide us with a great, lush screen. Someday I'd like to try making some homemade beer, and would love to be able to use the hops we grow in that.

Off subject some, but I like to try and "grow" my soil (so to speak). This year I plan to plant some alfalfa; to use in making compost. (we are fortunate to have the space for such an endeavor)

Here is a link that might be useful: John Jeavons article - this guy is a soil grower big time

Ditto to the person who said Chard. I like anything that is densely nutritious, survives nearly all weather conditions, and keeps producing all season from a single planting!

Plant once, harvest a few outer leaves from each plant at a time, and enjoy fresh salad and sandwich greens, stir fry and sautee greens, and soup greens, from Spring til frost!

Hoping for chard. It is my first year.

Garlic. It is expensive here, but very easy to grow. Grows during the off season. Wow.
Peppers. More expensive, a little harder to grow.
Tomatoes. Not expensive, but simple to grow. No pests really.
Potatoes are great. They can be stored a long time if you take some care.
Here is a surprise for you. LETTUCE!!! Save your seed, and it is cheap cheap cheap.

I grow other things. Asparagus is great, but space is really at a premium where I live, so I am ambivalent. Considering the time and trouble, expensive things like broccoli and cauliflower are not worth it for me. Pumpkins are very easy, very good, and store well, but the space is still hardly worth it.

You can find many official sources with this information on the web.

I have to go with tomatoes too. For 3ftx3ft space per plant I get about 20 lbs of fruit, and during the season I eat about 1lb per day fresh, and in the off season we eat probably 1-5 lbs per week of frozen sauce or frozen tomatoes. Even if a Zucchini did produce that much fruit for that amount of space (can you gow zucchini in a tomato cage? I just couldn't eat that much of it. Same for Chard. Potatoes are a possibility, but I would have to switch over from Pasta, and then my tomato consumption would drop. From an economic standpoint, heirloom tomatoes are $3-$5 per lb, Zucchini is $1-2, Potatoes ~$1, so each tomato plant is giving me up to $100 of food per plant.

I live in southern TN, 6b, and I wanted to ask about planting chard now. It's already warmed up, should I wait and make it a fall crop? Will that work? I've never grown swiss chard before, but after reading these posts I'd like to give it a try. I'd love to be able to give my family fresh, organic greens of any kind. However, didn't have the garden ready this spring, and I'm getting a late start.
Oh, I'd say tomato plants, started from seed, indeterminate and cherry, you get lots of them, enough to share and give away! Nothing beats the taste, either.
Do any of you save seed from your vegetable gardens, or flower gardens to plant out next year? If so, how do you do it successfully? Thanks, you guys are great.

After consideration, cherry tomatoes.
Where I live, they are anywhere from a dime to a quarter apiece, and last year, I had a small shopping bag of them that I took on a day trip with four kids. They disappeared quickly.
Garlic is 1-2 bucks a head. Peppers and Tomatoes can get up to a buck each.
I guess we all have different criteria. I could make an equation, probably, but the best bang for the buck would be a veg: grown easily in a small space, off season, using few nutrients, producing useful expensive food that can be stored for some reasonable time.

For me, garlic is the only one that fits all of that, and it keeps for months. Chard would be second place if it could be grown year round AND produce seeds, but ch. toms are number two right now.

OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
Saving seed is easy. There are details, but basically, save the seeds the plant produces. Let them dry. Store them. Use them. If it were hard, plants could not do it. They do. You can too. Just do it.
Obvious exceptions are potatoes and garlic, which grow faster if you do not use seed.
I save seed for peppers, toms, beans, garlic(cloves), potatoes(seed potatoes), squashes and pumpkins, lettuce, carrot, broccoli, radish, onion, etc.

Saving seed for tomatoes is a bit different than for fruits that have "dry" seed. If you just want a couple of tomato plants for the next year you can dry some seeds, goo and all, on a peice of napkin, plastic etc. If you want to save the seeds from an entire tomato for longer storage or trading you have to get rid of the goo. The simplest way to do this is called fermentation. Cut the tomato in half and squish the seeds and juice into a wire strainer over a bowl. Take a rubber spatula and squish/rub some of the gel off of the seeds and through the strainer (this speads things up a bit and makes it a cleaner process). Put the seeds into the bowl and add some warmish water. Cover and let rot in a warm room temp area for 3-4 days, rinse the seeds off (the wire strainer and kitchen sink sprayer help) and dry on a paper plate or coffee filter for a few days. The seeds will be nice and clean and fuzzy at this point.

People doing large quantities simply squish whole tomatoes into a bucket and add water and let it rot for a few days. The good seeds sink to the bottom and the bad seeds and rotting fruit float above in the water when the mess is swirled

Fermentation works for goopy pumpkin seeds to.

Novice2009. You can plant chard now. I'm in southern tn and I find chard grows much better than spinach here and will produce year round except for the hottest part of summer. I let it go to seed and always have volunteers from it to replant elsewhere.
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I plant lots of zuchini and summer squash. We eat lots fresh, but freeze most. When the freezer is full, dehyrdrate the rest (and certainly those that go too big) Those are stored and used in soups and casseroles all winter. They reconstitute well.
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Those tiny cherry tomatoes that volunteer like crazy have really saved my bacon during the drought. They produced when my fancy tomatoes didn't . When those died, I still lived on cherry tomatoes.
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Normally beans produce well for us.

For me, its the tromboncino squash. It does take a lot of space but it produces two types of squash. When it is young, it is a good substitute for zucchini. If you let it grow, it gets quite large (3 feet or so) and the squash tastes like a winter butternut squash. It is pretty hardy and withstands the assault of the squash vine borer and squash bugs. It is also quite an attention getter!

There's different kinds of "bang" for the buck.

From a pure compared-to-supermarket-prices perspective: shallots. I've seen shallots go for a buck each around here. I bought a bag of sets for 16 bucks years ago and save some back for replanting every year, so my cost per shallot goes down every year even as my crop size grew. As the numbers are currently working, each shallot I grow this year will cost less than two cents. Plus they are terrific to have in the kitchen (especially when they are cheap) and offer long storage with no special effort.

From a nutrition-per-square-foot perspective: potatoes. A ton of food from small spaces. Also superb in the kitchen, especially new potatoes, and interesting variety available. And also offer long storage without canning or freezing.

From a gee-whiz-in-the-garden perspective: Swiss chard. Grows from spring to fall, is hardy and likes cool weather yet also yields in summer heat, yields all season from a single planting, is easily grown and rarely bothered by pests (in my garden anyway) AND is best thought of as two vegetables culinarily (leaves and stalks)...whew, that's an impressive list of credentials for a leafy green! Collards come close, but I find chard easier to care for and more interesting in the kitchen.

But my overall champion has to be: tomatoes. Easy to grow. Prolific plants. Great compared-to-market value. Almost mythical quality when garden ripened. Tremendous variety to choose from. And, for me, without a doubt the most versatile vegetable in the kitchen. They can find a place in breakfast, lunch, or dinner. They can be raw or cooked a million ways. Consider the number of cuisines they are at home in, and the number of roles they play in those cuisines, and the number of ingredients you can marry them to - it's amazing. So for me they are an unbeatable combo of money bang, garden bang, and culinary bang.

This year it is Kabocha squash, also known as Japanese pumpkin.
I threw out some seeds from a Kabocha out into an empty flower bed.....now I have many fruits on the vine and have required very little care.
I love the Kabochas because they are sweeter than pumpkins, very nutritious make great smoothies. The are about 85 cents a pound at the market, if you can find them, and mine weigh about 5 pounds so so.
I begged an almost rotten tomatillo from the market and threw it in some dirt and kept the place watered. Now I have lots of tomatillos blooming....and they re-seed easily.
Good for salsa and green chile sauce.

"May Night" salvia
orange african bulbine
ruellia
lamb's ear
obedient plant

~ freshair

Carrots and beets. I let a couple of plants go to seed and I am now swimming in them. I can't eat them fast enough. They have taken over the whole garden. I have even invited the local bunnies to come over and take some.
Clare

Matt's Wild Cherry tomato - 1000's of tomatoes, no pest or disease problems, self-seeds prolifically (I never plant it, just don't weed it from the parts of the garden where I want it to grow that season). My garden would be a cherry tomato jungle if I let it have its way.

Jeruselum artichoke - completely takes care of itself, just dig the tubers when you need them. Will also self-seed itself around the garden and yard if you let the flowers mature fruit.

hands down it has got to be Kudzu.

Huge starch root that is edible and medicinal.

animal fodder from leaves and are edible to humans

rope from the vines is better than hemp

Make paper

Make cloth

Bio fuel

The list goes on and on...

It's asparagus, hands down. $10 will buy you 10 crowns. Two people can eat asparagus for 25 years.