Beans and peas have protien, as well as peanuts. These you can grow in a garden. Peanuts may not grow well up north. Hickory nuts are good, but you will need a hammer to crack them. Small game like the previous poster said, including chipmonks, squirrels, rabbits, snakes, frogs, lizzards all do have protein. You also need fat, which some animals lack enough of, especially rabbits. You can trap most small game, even a rat trap will catch a chipmonk. Snares also can entangle a squirrel if placed on a tree with a squirrel nest. Birds can be snared and trapped. You can catch fish in nearby streams, ponds, or rivers.
A backyard garden used year round can grow a tremendous amount of veggies. Build a small green house using bent pvc pipe stuck in a few concrete blocks and covered with clear plastic. You can grow summer veggies in there in pots and boxes, and start some plants early to transplant after frost. With plenty of seeds and non-hybrid plants for future seeds, snaring, trapping, using a pellet gun or cb's in a .22 rifle, one can survive quite some time. Long term will require a homestead in the country somewhere with good relationships with neighboring farmers and homesteaders for survival. If you buy an eatable plant guide book or cards, you will be surprised as how many eatable wild plants are in the woods. Even grass seeds, and roots are eatable.
Just in the woods near my home inside the city limits are chipmonks, squirrels, rabbits, muskedines, hickory nuts, dandilions, kudzu, wild violets, wild onions, snakes, fish in a creek (my son has caught bream out of there), lizzards, toads and frogs, lots of insects (katydids, grasshoppers, and crickets are eatable). Most people would not eat some of this, but if you are hungry and it is all that is available, I could survive. You can even make a drink like coffee from roasted dandilion root ground up and brewed. A little wire to make snares for the small game. My grandfather made a quail trap out of sticks made into a box and tied at the corners. Put some chicken feed inside with a little tunnel going into it. Quail got in, but tried to fly out. They couldn't figure out how to go back through the tunnel under the box. It is illegal to trap them, but it can be done in a survival situation. He did something similar for rabbit traps, but put the trap on flat rocks so the rabbit couldn't get out once the box fell. Used seeds and such to catch rabbits. They tripped the triggers, and down went the box. Rabbit couldn't dig out because of the rock around the edge, and he put a big rock on top of the trap so it couldn't move the box.