Not an expert, but it looks like a single coreopsis to me. It comes in a double that I've grown. Guess that isn't really a wild flower through. Unless it's the native from which the newer ones were bred. I've heard them called tic flower I think.
KY Zone 6
From: Jean M. RICHTER <email@example.com>
To: iris-photos <firstname.lastname@example.org>
Sent: Sun, Oct 31, 2010 7:44 pm
Subject: [iris-photos] OT: mystery flower
Here I am displaying my ignorance of wildflowers - my housemate was a bit slow to plant her raised bed in the front yard, so after getting tired of looking at bare dirt, I decided to plant some wildflowers (a "beneficial bug mix" from Gurney's). Unfortunately, this one wasn't listed on the seed packet, but I bet the botanical experts on iris-photos know what it is :-)