View photos of the edible plant Olneya tesota (Ironwood), profiled in Sonoran Desert Food Plants.

A passage from Sonoran Desert Food Plants:

Early to mid–summer the dried bean is collected, removed from the pod, and eaten as is: they are crunchy–chewy at this point and are not astringent. They also can be prepared like any other seed/bean – soak, rinse, and simmer until soft.