Coatbuttons, an introduced species, has been added to the USWildflowers database (02/20/2012.) Scientific name is Tridax procumbens.  Photo below was taken in Sarasota County, FL, on December 18, 2011.   It  is also known by the common names Tridax Daisy, Tridax, and Cadillo Chisaca.  Go to the Coatbuttons detail page for more photos and information.

Coatbuttons, Tridax Daisy, Tridax, Cadillo Chisaca - Tridax procumbens