Like a dog tail? Maybe a fox tail? They aren't 4 feet long, though. That's bizarre.
When I pulled it out, it was about 6 inches into the ground, so I'm guessing that whatever it was, it either didn't make it to where it was trying to go or it had a detachable tail. The rest of the tail was flat across the ground, so it was probably there for a while. I just never noticed it.