This, I'll be adding significantly to as time passes. DO NOT try any of these until you've verified what I'm recommending by doing a little research yourself! Check my book list for some of my favorite references.
VEGETABLES and other FLORA: Dandilion and Curly Dock Greens; Wood Sorrel -for a bitter salad topping; Purslane (one of my favorites, either boiled, steamed or raw; Spiderwort; Day Lilies; Wild Onions and Garlic; Wild Fruits and Nuts;
DRINKS: Steeped Sumac Berries (NO, NOT poison sumac. Use only red, upright sumac berries.); Dried Goldenrod and Horsemint (Bergamot) tea; Chicory Root Coffee (Dandilion root tastes about the same, but you have to collect so much more of it.) -dig, THOROUGHLY WASH, roast 'til brown and hard, chop, and brew as you would coffee, but use only about a third or half as much -it's got a strong flavor. The color isn't quite as dark.
And there's always wild fish and game! Snapping turtle is particularly good, but it's a pain to kill and clean. I fry or boil the meat. You don't have to make soup.