It's an Eastern US native (formerly Aster oblongifolius, now Symphyotrichum oblongifolium). Asters have been split up into three genera now, following modern taxonomic techniques, and their new generic names sound unfamiliar, but are accepted.
The flowers on these plants are currently covered with honeybees, bumblebees, and butterflies, and they make a wonderful addition to the fall-flowering asters to use in gardening, as they're low and spreading. This looks like a great plant!
