My younger daughter recently did a school science project tabulating insect visitors to a selection of a dozen various flowers. This small butterfly was plentiful in our yard, visiting the small yellow flowers in our pesticide-free lawn, and more rarely visiting the Blue Salvia in our test group. I wonder if this is the Little Yellow (Pyrisitia Lisa) or the Mimosa Yellow (Pyrisitia nise). I think the photos I've found of the latter are a closer match, but http://www.butterfliesandmoths.org/species?l=1453 shows their range to much further to the south of us while the former seems much more widespread, including our county. I assume I have photos of both sexes.