I think this plant may have cross pollinated in my garden. It's in the mint family. I think it's anise hyssop/spearmint but I'm not sure. The leaves look kind of like spearmint, only larger. if I remember correctly, the large ones were about the size of a half dollar. It has a minty anise smell. The flower you can see and they grew on a stalk kind of like basil.
I was able to get a few seeds from it, and am hoping that is is perennial to my area, it's a pretty plant.
You will have it forever! It seeds all over the place, but you can easily pull out the baby plants. My sister uses it as a ground cover under the trees with surface roots, where she can't plant anything else.