Good Morning,

We moved into this house 2 years ago in May. Every spring/summer we seemingly spend hours trying to pull these guys out of the larger garden in our back. It's a beautiful garden, overrun by whatever this is. I've tried a 3in layer of mulch with no luck. Just pulling them seems to be the only way. The picture is of the new growth so far this spring. They get much taller than this, and spread over our entire garden. They seem to be a single stem that bunches into multiple stems, not a vine. What is it!?!?!? I'm in Baltimore, MD zone 7b