These large beetles are common amongst leaf litter in early spring. The female, as here, is very large and heavy bodied, the males are smaller and typically have a swelling in their antennae at the mid-way point. They are also called oil beetles because they emit a rather stinky oily substance when disturbed. This can cause a blistering on the skin if it gets on you. I put this one on my shoe to get a better shot, as she kept disappearing under leaves.