None of those posts actually answer dude's question about WHAT to grow. In cold weather (which is usually less populated and better to run to) Root and leaf crops do best. Carrots, Onions, Potatoes, Chard, Kale, Broccoli, Beets, Radishes, cabbage, lettuce... If there's snow you're best off with root crops.
Summers (if night temps are above freezing) can handle tomatoes, melons, chilis, cucumbers, zucchini, etc...
You're a pretty good bet with potatoes and onions about anywhere decently cold though.
Celery extracts salt from the ground, which you can then extract from the celery.
Native American references will likely give you a good idea of uses of native plants as well.