Among other things, I pulled some Garlic Mustard, which is just starting to bud down here in Dayton. I encourage people to look into volunteering to pull it up in your local parks and, indeed, to pull it wherever you see it, in the next couple of weeks as the little white flowers on it are opening and before it seeds. Then -- important! -- do not put it in compost piles. It will finish going to seed. Put it in plastic bags and throw it away.
The native plants of north America will be thanking you.