Summer medicinal and edible wild plants.?

I have studied wild plants that can be used for edible and medicinal purposes for quite some time now, but it's been mostly just studying and I haven't put much of anything to use. I tried harvesting some acorns in spring to make flour and get some tannin for medicine use, but realized they were all bad and have to be harvested in Fall. It only then hit me that, I know all the uses of all the plants, but they have to be harvested at different times! What a stupid mistake . . . anyway, so I realized that most of them are harvested in Spring or Fall. . . are there any good ones for the Summer? I like the very practical ones, ones that are everywhere but provide lots and lots of uses. Like cattail and acorns and willow trees. What can I walk into the woods in the summer time and just pick up and put to many uses? I live in Ft. Wayne, Indiana, not sure what zone it is, but I also travel to MI and IL, often.