This is Trillium -- aka wakerobin, tri flower and birthroot. One species of this wildflower is the official emblem for Ontario, Canada. It's native to temperate parts of North America and Asia. I have found it growing near streams in western North Carolina and eastern Tennessee. Interestingly, if you pick trillium, you can do serious harm to the plant. It prevents the plant from producing food for the next year. It can take years to recover.