Here is something good to know for these frugal times. This list comes from TipHero, where you can find the complete explanation of the benefits of each of these healthy foods.
You will notice that these foods, for the most part, come with a minimum of packaging, which makes good economic and recycling sense. Rice, oatmeal, popcorn, nuts, and dried beans can all be bought in bulk, so that just leaves eggs that come prepackaged.
water (don't buy water in plastic bottles--filter your own)