A core foundation of any self-sufficient lifestyle is the concept of food production. Food grown in your own garden is like an insurance policy. If and when you find yourself in a disaster or emergency where either the store-shelves are bare or maybe you can't get there at all, your garden will be there to support you. This is especially true is you've taken the very prudent extra initiative to preserve and put up your excess via canning or other methods so that you'll have it even after the growing season is long over. Also, when eating food you've grown yourself, you know exactly what it has been exposed to from the seed up; commercial foods are nearly always dowsed in who knows how many kinds of pesticides and other chemicals - the food you grow will be better for you.
Depending on the length of the emergency or in the event of all-out TEOTWAWKI (see glossary) scenario, it may be important to not only be sure you and your family can eat but also that what you're eating is providing you with sufficient nutrition in the form of vitamins and minerals. By and large, we Americans are often woefully deficient in vitamins and minerals in our diets in the best of times, nevermind how bad it would most likely be if we could no longer just run over to GNC to pick up a bottle of multivitamin supplement pills. Therefore, it is best to plan your garden in such a way as to provide you with true self-sufficiency in bad times as well as all the time.
There's lots of information to be found on this subject on the internet - far too much to cover it all here. I will try, however, to share a few things I've learned in order to get you started. First off, one tip that is easy to remember is that the richer the colors the better. Dark, deep greens as well as bright colors like red, orange or yellow (the brighter the better) are typically the really vitamin- and mineral-packed goodies. Some examples that fit this bill are peas, corn, pumpkins, beans and spinach or-- even better yet-- kale.
Typically all of the green, leafy vegetables are rich in vitamins but they tend to come up lacking in caloric value. It is actually possible to starve if you eat them alone in a phenomenon not altogether unlike that of "rabbit starvation." Therefore, calories and proteins should be your other priority. Some of the foods listed above will help in this area as well as being vitamin-rich, but another crop you should seriously consider is potatoes. Potatoes contain a significant amount of protein, plus vitamin C and other nutrients. It is, in fact, possible to survive on potatoes alone, if you include the peel. It is a sad truth that a majority of the nutrients in a potato are located directly beneath the peel and as such they are often cut off prior to cooking. Potatoes also keep comparatively well and with minimal work on our part, generally speaking.
Sharing a similar name is another outstanding crop you should consider planting. Not long ago, the Center for Science in the Public Interest ranked the sweet potato at the top of their list of nutrition of all vegetables (source: http://www.foodreference.com/html/sweet-pot-nutrition.html).
Again, this article is by no means an all-encompassing source of information on this topic, but I thought you might find it a useful start. If you've already made the decision to grow your garden for the coming lean times, it makes sense to grow it in a way that will allow it to properly sustain you and yours should it become your primary food source.
For More Information -
World's Healthiest Foods site: http://www.whfoods.com/foodstoc.php