This is the Western Trillium, Trillium ovatum, photographed in the Leavenworth, Washington, area, but near the end of its season. The flowers are white but take on these red-purple tones as they begin to fade, turning completely purple just before falling off.

ronaldhanko-orchidhunter.blogspot.com/2013/05/orchid-hunting-in-leavenworth-area.html