In addition to grains, The Church of Jesus Christ of Latter-Day Saints recommends beans for longer-term storage. Beans are a fantastic protein source and are the perfect complement to many of the grains all stored. In fact, beans and rice (or beans and cornbread) make a complete protein which is full of amino acids and all sorts of good stuff.
Our family really likes black beans and refried beans -- so that's what we've stored. I've actually stored both pinto beans as well as canned refried beans. I categorize my refried beans into my three-month supply and the pinto beans count for longer-term supply. I also store a smaller supply of northern beans, white beans, navy beans, as well as pork and beans. I have a bean soup "dump" recipe that calls for all of these so I rotate a few in and out of my storage each month. Pork and beans are great to have on hand for family picnics and also work for 72-hour kits (especially if they have a pull-tab).
Beans are not cheap. I've seen them recently for about $50 for a bucket of 25 lbs of beans. The church cannery offers them more cheaply. It's cheaper to buy the beans in bags and dump them into a bucket (with a gasket lid). The Provident Living website states that the beans will store for 30 years or more. You should store 5 lbs. of beans per person per month (or 45 lbs for a 9 month longer-term supply).