False Pennyroyal, a native species, has been added to the USWildflowers database (09/26/2011.) Scientific name is Isanthus brachiatus.  It is also known by the common name Fluxweed.  Photo below was taken in Walker County, Ga on September 24, 2011.   Go to the False Pennyroyal detail page for more photos and information.

False Pennyroyal, Fluxweed - Isanthus brachiatus