Restricted Noxious Weeds 
Agronomy 105's Weed ID
Wild mustard
Wild mustard is an annual or winter annual that reproduces by seed.  In Indiana it is primarily a problem in small grain fields. 
It has a branching growth pattern and a very irregular leaf shape.  Wild mustard can be differentiated from its relative, bitter wintercress by looking at several characteristics.  Wild mustard plants will have some pubescence on their stems while bitter wintercress will not.  Both of these plants have yellow flowers, but wild mustard blooms much later in the season than bitter wintercress. 
The small, smooth seeds of wild mustard are round, black to brownish-black in color and very hard.