Whorled Leaf Coreopsis, a native species, has been added to the USWildflowers database (05/28/2011.)  Scientific name is Coreopsis major.  Photo below was taken at Reflection Riding in Hamilton County, TN on May 27, 2011. 

Greater Tickseed, Whorled Leaf Coreopsis, Forest Tickseed – Coreopsis major