Potatoes, potatoes, potatoes. They will grow anywhere and they have complete amino acids. Add in a few vegetables, garlic, onion, etc. The fact of the matter is, most people don't know enough about gardening and don't have nearly enough land to support themselves. The best thing you can do for your own security is to supplement your trips to the grocery store with fresh food you grow yourself. Have a couple of chickens for eggs. Trade stuff with your neighbors. Someone is going to have an apple tree and you have a bag of potatoes and some nuts and eggs. The barter market could come back.