Blast has a good idea. I know of one plant that would provide a decent amount of sustenance, even if you only used it because it attracted critters. Chufa is a plant that forms a starchy tuber like a cross of a potato and a peanut, and the tuber is edible. It also attracts deer and turkey, so it might help stock the freezer.

You might already have and should be able to grow ramps.

Have you considered stocking the pond? You could probably stock with a number of fish. Channel cats should work and there is a lot of info available on raising them.

Finally, if you really want some trees gone and cannot cut them down legally, considering putting a couple pigs out there for a short while where you want the garden. They will clear out trees and leave fertile soil behind.