Reddit reviews A Field Guide to Edible Wild Plants: Eastern and central North America (Peterson Field Guide)

If you can buy a food dehydrator, perhaps you can just make jerky. It can also be made in the oven. I don't know if there's something besides convenience and protein you like about protein bars, but if that's all it is, jerky is convenient and full of protein.

I empathize with inability to grow. I live in a studio apartment and I tried to grow herbs in the window. They just didn't thrive. They'd shoot up from the seed, turn pale, and fall over. My only window is a south-facing window with large trees in the way. There might be other ways to grow your own though. Perhaps a neighbor or a friend would allow you the use of their land in exchange for part of the harvest.

There is an excellent website and youtube series called "Eat the Weeds" on foraging. In fact here's a video on acorns and another on acorn grubs. If you're already used to buying and cracking whole nuts and making nut butter and flour from them, then doing the same with acorns might be especially to you.

Here is the field guide I use for identifying plants. Here's a list of plants with some edible parts that you may be able to research foraging in a city:
morel, hen-of-the-woods, chicken of the woods, asparagus, sow-thistle, wild lettuces, clover, sorrel, burdock, thistle, nettle, amaranth, dandelion, wild onion, chufa, sunflower, strawberry(make tea if the fruit is gross), mulberry, oak, japanese dogwood, purslane, chickweed, milkweed, roses, yaupon.

There are people that will grow fruit trees in their front yard and then let the fruit fall off and rot. You could always knock on someone's front door and offer to take their fruit off their hands. Look for apple, crabapple, peach, fig, cherry, walnut. I also see a lot of "ornamental cabbage" in gardens which is in fact a kind of kale that is just as edible as the kale in the grocery store but which people do not eat.