Looks like mugwort to me - artemisia. It spreads by underground runners, which you must dig up to have even a hope of getting rid of it. It's horrible stuff. Some of the roots were close to a foot underground when my neighbor and I made a concerted effort to get rid of it. It took two full growing seasons, but it was over about 20 feet of garden. Since you've got the house on one side of that, you may have an easier time. Good luck!