Anne Elliott's photos with the keyword: Sanguinaria canadensis f. multiplex Plena

Several years ago, I saw this plant species growing in someone's garden. I thought it looked a fascinating flower and hoped to see it at the Reader Rock Garden some day, as it is included in their list of species for their gardens. When I called in on 6 May 2015, after a volunteer shift, there it was! I guess this must be the double version of the flower. Just checked my photostream for Bloodroot and found that I had seen this plant at Reader Rock Garden before, on 11 May 2009. Have added a photo that was taken that day, in a comment box below. Shows a much nicer flower.

I noticed this pretty, white flower at the Reader Rock Garden, but I have no idea what plant it is. Does anyone know the ID for it? Would be great if someone can help - thanks! Later: thank you, Doug, for the ID - Sanguinaria canadensis f. multiplex Plena (double Bloodroot).