Rice. This is an old standby. It can form the base of many tasty and nutritious meals. Be aware that although it requires no processing, it does require quite a bit of water to cook. It is most economical to buy rice in 40 lb bags and repackage it into buckets yourself, a 5 gallon bucket will hold a 40lb bag. For a bit more you can find rice sold pre-sealed in buckets from a number of sources.
Just be aware, if you have stored mixes like bisquick or cake mixes which have baking powder in them. Baking powder has a shelf life, after that shelf life, the bp isn’t stable so your product may not rise and/or may taste funny. Depending on what form of dry milk (powder as opposed to instant milk) is used, that can also make your premixes go bad.
In the previous decade, preparedness consultant, survival bookseller, and California-based author Don Stephens popularized the term retreater to describe those in the movement, referring to preparations to leave cities for remote havens or survival retreats should society break down. In 1976, before moving to the Inland Northwest, he and his wife authored and published The Survivor's Primer & Up-dated Retreater's Bibliography.
Neutrons are emitted only during an active fission process, such as that taking place in a nuclear reactor or at the actual moment of an atomic explosion. Neutron activation that is structurally significant takes many years, and is only a concern in materials that will be used to construct things like nuclear reactor vessels. This is in no way a concern when choosing structural material for a shelter.

This past September, Wise Company’s products proved lifesaving in a very urgent sense: Strapped for rations following the double whammy of Harvey in Texas and Irma in South Florida, FEMA placed an order for 2 million servings of food to relieve Maria’s victims in Puerto Rico. On a typical day, though, its selection of 72-hour, one-week, and one-month survival kits, packaged in boxes that can easily fit under a bed, seems more geared toward everyday Americans looking to prepare for the unknown.