Looks like Canadian thistle to me. It's very aggressive. I pull on site. The bottom of the stem is often soft enough for me to touch without becoming holey.
Oh, and how to get rid of them is wear them out by pulling as soon as you see them. People often neglect these because they are tough, but then it just gets worse. I don't do poisons.
Work smarter, not harder.
A nature documentary filmed entirely in a pet store. This tiny ad was in an aquarium