I live in the Arizona desert. Before the white settlers, a major food staple was the mesquite tree bean. The tree thrives in the desert, and it produces bean pods with rock hard beans. The traditional way to process it was with a metate, basically a stone mortar and oblong pestle. Machine processing tends not to work because it gets gummy. The bean provides a complex carbohydrate that is especially good for maintaining blood sugar levels. Used mostly for bread I think. For more information, contact the Tucson Botanical Gardens.