We found this plant blooming in December at the Cuddo Unit of the Santee National Wildlife Refuge. Plant was growing in the center of one of the trails.
sorry for the tardy reply! Your plant is most likely Pityopsis graminifolia (Michx.) Nutt. var. graminifolia, narrowleaf silkgrass. It has also been called Heterotheca graminifolia. However, it could alternatively be called Heterotheca nervosa, apparently a synonym. I cannot be more certain, because glands hidden by the hairs are often needed for a really precise ID, but we seem to be dealing with the same plant with different names anyway.
Dr. Steven Hill, Botanist, SCNPS