This is a description from University of Hawaii.
"Flowers solitary at leaf axils, in clusters at end of branches, yellow to yellowish orange, often red at the base of the petals, 0.33 inches diameter, flower stalk slender, to 1.5 inches long"
Sida rhombifolia is the only species reported in TK's county and the closest match I can find of any species that grow in Texas.