This small green plant most often seen in moist shaded and wooded areas is called miner's lettuce because it was eaten as a salad or boiled like spinach. The Native Americans made a tea from the leaves used as a laxative.
The almost-round leaves are actually two leaves which have fused together during growth. Take a hand lens and look for the small "seam" between the two leaves.
Several patches of miner's lettuce can be seen near the creek at the seasonal bridge, at the Pourroy Garden, and on the trail embankment between the Ravine Bridge and the Pourroy's Picnic Area.