This plant should be named "hiker's surprise". It is found in the swamps and lowlands of the Southeast.
One of approximately 130 species found mostly in swamps, streamsides, and lakesides of tropical regions and South Africa the swamp lily is the only one native to North America. Not actually lilies but members of the amaryllis family, many Crinum Lilies (not this one) are cultivated for their large, showy, funnel-shapped scented flowers.
The American cousin, however, is only found in southeast marshes, swamps, and lowlands and enjoyed by hikers from May through November.
The white flowers rise from a leafless stalk and according to a number of wildflower books can be one to three feet tall. I've never seen them taller than one foot.