I never see rabbit-foot clover (Trifolium arvense) in Pittsburgh but it’s easy to find along the roadsides in Maine (where I happen to be).

Originally from Europe, it prefers dry sandy soil, field edges, and waste places.   This beautiful specimen was photographed in Estonia.

You can see how the flower got its name.

(photo by Ivar Reidus via Wikimedia Commons.  Click on the image to see the original.  This was a featured photo in August 2013.)