If the worse happens and you need to supply your own food, stores can last awhile, but it'd be better, assuming no contamination, to grow your own.
Which foods though?
You'll want a complete nutrition profile, you'll need your vitamins. So sweet potatoes would be a good choice. Very hardy, extremely high in vitamins, and I read that the first jamestown (or maybe it was the pilgrims) more or less survived on sweet potatoes the first year. They also provide a good amount of calories.
Asparagus doesn't provide a whole lot of calories, but they are a perennial vegetable, when most are annuals. Not having to worry about saving and protecting seeds every year has got to be worth something.
For fruits or berries I like raspberries. They are very hardy, will tolerate poor soil, spread like mad, and produce all summer long. You will get a good harvest with minimal effort.
Then of course there are nuts. Nuts last a long time, and pack a good amount of protein and essential fatty acids. Planting a nut tree would definitely be a good investment.

