Golden Coreopsis, coreopsis tinctoria

"Plains coreopsis, garden tickseed, golden tickseed, or calliopsis, Coreopsis tinctoria, is an annual forb." -Wikipedia

From Roadside Flowers of Oklahoma by Doyle McCoy:

Composite family. The stems are branched and 1-4 feet tall. The leaf blades are once or twice divided into leaflets that are very narrow. The heads are numerous, about an inch broad, and have brownish inner bracts. The rays are yellow with brown bases, three lobed at the tips, and about a half inch long. The central disk flowers are yellow to brownish, tubular, regular, and five-toothed. They are widespread and prefer low wet places. May - September.