Rattlepod

Crotalaria is a genus of herbaceous plants and woody shrubs in the Family Fabaceae (Subfamily Faboideae) commonly known as rattlepods. Some 600 or more species of Crotalaria are described worldwide, mostly from the tropics; at least 500 species are known from Africa. Some species of Crotalaria are grown as ornamentals. The common name rattlepod or rattlebox is derived from the fact that the seeds become loose in the pod as they mature, and rattle when the pod is shaken. The name derives from the Greek κροταλον, meaning "castanet", and is the same root as the name for the rattlesnakes (Crotalus).

http://en.wikipedia.org/wiki/Crotalaria