Spiderwort – these range from pink to blue; the flowers open only in the morning, then (according to the Audubon Society Field Guide to Wildflowers) the petals wilt and turn into a jelly-like fluid. (Lucky for me, I snapped this picture at 11:57 AM!)
Great shot with the drops of water on the petals! This looks like a Virginia Spiderwort, according to on-line resources I used.