Wild Radish

(Raphanus raphanistrum) - Bombay Hook NWR (Nov. 27, 2006)

Basal rosette, leaves highly lobed, covered with stiff hairs, seed pods break into fragments.

Wild Mustard (Brassica kaber) and Yellow Rocket (Barbarea vulgaris) leaves aren't as divided, lack stiff hairs, and their seed pods open straight down the middle

http://oak.ppws.vt.edu/scott/weed_id/rapra.htm