Nodding Trillium aka Whip-poor-will Flower (Trillium cernuum)

2015-5-16 Mt. Cuba Center, Hockessin, DE
http://www.alabamaplants.com/Whiteopp/Trillium_cernuum_page.html
http://www.wildflower.org/gallery/result.php?id_image=19212
http://wisplants.uwsp.edu/scripts/detail.asp?SpCode=TRICER
https://gobotany.newenglandwild.org/species/trillium/cernuum/
gobotany says flowers can be red to pink, white