Micranthes micranthidifolia is a member of the Saxifrage family with the common names lettuceleaf saxifrage, branch lettuce, brook lettuce and bear's lettuce. It grows in wet areas and mountain streams.
It is a native plant of the Great Smoky Mountains and occurs in many other parts of the southeastern United States.
References
Horn, Cathcart, Hemmerly, Duhl, Wildflowers of Tennessee, the Ohio Valley, and the Southern Appalachians, Lone Pine Publishing, (2005) p 143,