No, I don't fear a zombie apocalypse, nor do I adhere to a prepper mentality. But I do believe that emergencies can appear on the horizon when we least expect them (you just lost your job, or you're stranded by severe flooding for instance) and that we might be required to be self-reliant for a time with absolutely no forewarning. Also, I love the thought that I could care for myself and my family for quite awhile with what I normally keep stashed in my pantry--pretty much since I became an adult, I've always had at least a six month supply of the basics sitting on my shelves. And what with our gardening efforts and tending livestock, I figure we'd be pretty good pioneers should the need arise.
The subject is deep and wide, but today I'm going to list a three-month basic food supply. It's not perfect, but at the least you'll be able to start getting a handle on what your needs are. And these basic supplies can be bought for less than you might think. Added to that, most of these supplies will sit on a pantry shelf for years if they stay relatively cool and you keep them in a dark place (like a closet).
50 lbs. white flour, or 100 lbs. if you can't grind the 50 lbs. of wheat berries listed below
*50 lbs. wheat berries (so you can grind into flour)
*10 lbs. dried corn (popcorn works great) to be ground into cornmeal as needed, or 10 lbs. cornmeal
*25 lbs. oatmeal
20 lbs. white rice (brown rice turns rancid sooner than white)
15 lbs. pasta noodles (or 15 lbs. Durham wheat berries to grind and make homemade noodles)
25 lbs. mixed dry beans and legumes (such as pintos, white navy, red kidney, lentils, and split peas)
20 lbs. sugar
5 lbs. salt
3 lbs. dehydrated whole eggs if you don't raise chickens
1 gal. cooking oil (olive or vegetable, or a combination)
2 large jars peanut butter
12 lbs. powdered milk (comes in 4-lb. boxes)
1 lb. baking powder
1 lb. baking soda
5 lbs. yeast
1 gal. vinegar
1 lb. sprouting seeds (alfalfa and broccoli seeds are small, tasty, and easy to sprout)
*Wheat flour, cornmeal, whole oats, and brown rice don't last nearly as long as do their cousins (white flour, whole dried corn, oatmeal, and white rice). So if you have the ability to grind grains, wheat berries (which grinds into whole wheat flour) and dried (pop)corn (which grinds into cornmeal) will last years on a food supply shelf and not go rancid.
Now of course, I've made no mention of meats or other canned goods nor spices--this list is just the very most basic supply. Along with about a gallon of water per person per day, you could get by. Boring, yes, but workable. The only odd item mentioned is the dehydrated egg powder. I included this for a good reason: if you don't raise your own chickens for eggs, you'll need them in dehydrated form because without eggs you couldn't make pancakes, waffles, cookies, muffins, puddings, or egg noodles, etc. So raise some egg layers or buy the dehydrated eggs. You'll be glad you did.
If you've never sprouted seeds, they're easy. You can buy sprouting screens to fit on quart canning jars, rubber band pieces of nylon stockings to the jar lid, or spend more money and buy fancy sprouting kits. Whichever way you choose to go, get that taken care of soon and practice some so you understand the process. Sprouted seeds are incredibly nutritious. You can put them in your food or just eat them plain--about 1/8 cup per day or so would be plenty, but eating more is even better.
This list isn't the only answer to putting food by for an unforeseen emergency. But at least it will help to give you a good start. And while you're thinking about this subject, consider what foods your family enjoys and add those items into your stash. I'll give you an example: I don't think my family could be happy if we didn't have tomato based foods regularly (spaghetti, Mexican beans and rice, tomato soup, etc.) so of course I add that to my pantry shelves. I'm also a big one for canning meats of all kinds along with stew, chili, soup, and such.
I hope you'll take some small steps today to begin putting together a hedge against unexpected circumstances. Because I'm pretty certain that it's not if something happens but rather when.
Love your family well!