This butterfly we encountered on a hike with the family. The poor guy looks a little worn down and that made its identification a little difficult. After consulting an expert (my boss) I decided that it must be an Eastern Comma (Polygonia comma).
That’s a pretty strange name for a butterfly. It comes from a small white 'C' shaped marking resembling a comma on the underside of its wings (see second image). A dark form of the comma is often confused with the dark form of another butterfly with a strange name, the Question Mark (Polygonia interrogationis). A similar marking on the underside of its wings looks indeed a bit like a question mark.
These butterflies hibernate, so you can encounter them all around the year, but their most active flying period extends from April to October. It likes to feed on sap running from trees and sometimes sits on the ground, usually with the wings closed. Seems that we got lucky for our photo.