a widespread weedy annual plant (Medicago lupulina) of the pea family, with small yellow flowers and black seed pods, sometimes grown for forage
See black medic in American Heritage Dictionary 4
or black medick
noun
A cloverlike Eurasian plant (Medicago lupulina) in the pea family, having dense clusters of small yellow flowers and black pods. It is cultivated for forage. Also called nonesuch.