Oh, the photo is the 'before I left for 4 days' shot and before I cut it... I still cut it high though

Where do you live, and what type of grass do you have/did you overseed with? What probably happened is that your lawn had a fungal disease outbreak. Depending on the disease, your grass might come back in the fall, but probably not any seedlings that were affected.

By the way, seeding in June is the absolute worst time for cool season grasses, as you have discovered.

tiemco I live in Cambridge MA
Have no idea what seed was used before I bought the place but it was seeded by hand perhaps a year before we moved in
I have overseeded each Fall and Spring since then to try and crowd out the weeds 'organically' since there was a lot of crabgrass and this has worked well - I overseed with Penningtons sun and shade mix:
http://www.penningtonseed.com/en/products/smart-seed/sun-and-shade-mix
and patched with Penningtons 'patching' seed mix in the same sun and shade blend (I am guessing these are cool season grasses?)
Any better grass seed you recommend?
We have some big trees and most of the lawn gets morning sun with maybe a third of it getting a bit more up until early afternoon
I thought that perhaps the grubs had got to the lawn end of May/June because I suddenly had so many brown dead looking patches (it grew back beginning of Spring really well) but maybe it was a fungus since this happened very suddenly about 4-5 days after all the rain we had in May
I usually wouldn't overseed/patch in June but I had so many brown patches after what I thought/think were grubs that I wanted to try and fix it
If it is a fungus that has done this in the last 4 days (I just can't believe it looked so nice and then in 4 days looks half dead) what can I do? What can I apply to get rid of the fungus? Should I give it a really big soak or will that feed the fungus if it is that? Thanks for any thoughts/input

The entire east coast is suffering from fungal lawn diseases. Brown patch is the most likely candidate, but with hot, humid weather, and long periods of lawn moisture, it is creating an ideal environment for most summer diseases. Good cultural practices, proper watering, fertilizing, and mowing, can go a long way in preventing fungal diseases, and there are some organic/biologic preventative measures which help, but even with all that, diseases will rear their ugly heads when conditions are very favorable. Your June seeding, with the daily waterings certainly didn't help matters, and young grass is certainly more susceptible to disease. Green and lush looks great to you and pathogenic fungi. Right now the only way to prevent spread and new disease would be to apply a fungicide. Even though your grass is brown, that doesn't mean it needs a good soak, in fact that will help spread fungus. Watering your lawn should not be a daily thing. Once or twice a week, deep and infrequent is the key. Also when you are expecting days of rain, it would help to cut it before the rain, bagging the clippings, and cutting a bit shorter than usual. The good news is that most of the foliar diseases like brown patch don't kill off grass. It will kill the blades, but if the crowns remain intact, then most of it should return in the fall. Some diseases are root diseases, and those tend to kill grass. Pythium blight is a common one, especially on new grass. Pennington sun and shade probably contains some perennial rye, tall fescue, Kentucky bluegrass and fine fescue. Tall fescue is particular sensitive to brown patch, even some of the newest most resistant cultivars. Kentucky bluegrass does better against BP, but since your lawn is somewhat shady, and KBG takes a long time to establish, I would bet you don't have much of that in your lawn.

Thanks so much tiemco - I think you may be right.... I went for a walk this evening and a lot of lawns look like mine right now...and thinking back to the rains in May and again 4-5 days after the same thing - brown patches (so maybe not grubs after all)
So what is your fungicide of choice? I have been told about Immunox from Home depot - is that correct? If I treat in the next day or so will my lawn have a chance of coming back before Fall? Any down side to fungicides? ie for children or dogs? will it hurt the worms etc?
When should I water the grass again? Do you think the organic Milorganite that I applied was a bad thing or good thing or just neutral?
PS Do you have any recommendations of grass to sow come Fall that does well in New England and avoids these issues or at least does better during the summer months? Thanks again!

Immunox contains myclobutanil, which is the same ingredient in Eagle Granular fungicide. Immunox is a liquid, Eagle granular is a solid, so spreading it is a bit easier, but they do the same thing, you will save money buying the granular. Some of the best fungicides are strobilurins, namely Heritage G and Disarm G. They are pricey, but they last longer, and are very broad spectrum. Most of the newer fungicides are pretty narrow spectrum, only affecting fungus, and the amounts you use are very small, fractions of an ounce per 1000 ft. I'm not sure what the directions say about kids and dogs, but they are safe enough to be sold to home owners, just don't eat the stuff.

I would water when your grass needs it. Usually in weather like this that would be once or twice a week, again, deep and infrequent, usually right before sun up.

Milorganite is pretty gentle, and doesn't really produce a huge growth flush like sythetic fertilizers, so I doubt it was a factor.

No grass is immune to disease, regardless of the species. Shadier sites generally should be planted with tall fescue and fine fescues. Use cultivars that score well in the NTEP disease trials.

Thanks again for all this info - tried to upload a photo today for you to look at but had trouble... had a good look at the lawn (or seemingly what's left of it) today and there are also seems to be little 'holes' in the soil as well as these strange little mounds of dirt - perhaps 4-5 mounds of dirt like it has been churned... I am at my wits end - like I said mid last week before I left the lawn looked great and now...