I'm not sure what this plant is. It's growing in various spots in my yard in the mountains of Western North Carolina. It's got tiny little yellow flowers.
Looks like a weed to me! A weed is defined as something that grows where you don't want it to grow! If it is in several spots, then it is self-sowing and you will need to vigilant to eradicate it.
It's a Mustard Plant, a highly invasive weed here in Ohio. And probably everywhere else, too!