Pretty weedy plant.
You could probably just pull one, and plant at your house and have success.
problem is, spreads like mad from roots... (spreads by rhizomes )
This is one that will need constant thinning to keep in check...
Compare growing habit to japanese anemone, and showy pink primrose (Oenothera speciosa)...
Edit:
Any chance this stand was mowed during the summer?