plant ID help needed
Can anyone help me ID this. It may have come from some flower seeds I've sprinkled a couple years ago. I didn't plant it as a flower I would have bought. When I moved into the house four years ago it wasn't there (nothing was, a totally grass only yard). It came up one summer, and returned the next summer - in a different spot. Close to the original spot but several feet away and under a red maple tree.
It is the one with the purple flowers. It is tall and does it's own thing. I didn't water or touch it.
I'll include several pictures, if this site will allow. So you can see the flowers and the way it grows etc.
Thank you for any help you can provide!