Looks like one of the dock species to me, perhaps burdock. It grows a low rosette of leaves the first year and then sends up a flowering stem (not ornamental flowers) and then sends out tons of seeds to start new plants. I would remove it. It has a deep tap root, so a garden knife, screwdriver, or dandelion digger will help get the root so it is less likely to resprout.

It's burdock root. Very hard to fight because of the long root.