Hello, Dr. Hill,
This plant was photographed on 28 April, growing in the Fall Line in clay soil at the edge of oak/hickory woods, and getting more sun than shade. The leaves and leaf stems are quite fuzzy, the calyx too. The stem of the yellow flower has sparse hairs.
this looks to me like Ranunculus fascicularis, which in some books is merged with Ranunculus hispidus. A buttercup, but not one restricted to marshes by any means, it is often in dry woods.
Steve Hill, Ph.D., Botanist, SCNPS