I think? He wouldn't let me get close.
#42 Question Mark
Possibly another eastern comma? Does seem to be lacking some darker pigment on the edges, though, so not positive.
Kinder Farm Park, A.A. Co., MD Sept. 8, 2013.
I think this is a "Question Mark". The butterfly is backlit which obscures the lighter edging to the wings.
The Question Mark (Polygonia interrogationis) is a North American nymphalid butterfly. They live in wooded areas and city parks, or generally in areas which feature trees and free spaces. The adult butterfly has a wingspan of 4.5–7.6 cm (1.8–3.0 in). Its flight period is from May to September. "The silver mark on the underside of the hindwing is broken into two parts, a curved line and a dot, creating a ?-shaped mark that gives the species its common name."