Do they have to be vegetables? I would think lots of milk jugs full of perennials that bloom the first year would be a good choice. Then, when ready to plant in the spring, the children can plant handfuls around their vegetable garden.

Veggies are vital to school gardens--children should learn basic plant care skills so they know how to supplement their own plates. It's good that they know where food comes from--the ground, not the supermarket.

Cold season veggies are all excellent. Mesclun blends or leaf lettuce, spinach, peas, cabbage family plants, radishes, small-rooted carrots, beets, hardy perennial or biennial herbs all work well.