Perennial Buckwheat (Fagopyrum dibotrys)

This is a very easy plant to grow, that can spread.  The leaf tips can be cooked like spinach and the seeds can be sprouted and eaten.  Its grows many tall, slender shoots, and has pretty white flowers when it goes to seed.  This plant is pretty hardy and easily grows USDA Zone 7-10, maybe even zone 6.  Also has medicinal properties.