Carolina Satyr, Hermeuptychia sosybius, Penny/s Bend Reserve, Durham County, North Carolina. It was a cool day, and the butterfly would stop occasionally and turn perpendicular to the sun and angle up to bask.
This has got to be the most common woodland butterfly in my area. They have a long flight season, with multiple broods. It has apparenlty adopted the pesky introduced weed, Microstegium as a host plant--see Jeff Pippen's account. It is unfortunate that it does not make a dent in the weed's density--this is one of the worst competitors for native wildflowers, especially in moist bottomlands.