I live in NW Minnesota, on the prairie, but with a stand of trees behind my house. In this stand of trees I am sloowly removing invasive plants (buckthorn) and trying to establish native woodland plants. I came across this the other day, and have no idea what it is. At this point I only see the one plant.
This is growing in almost full shade, the soil here is heavy black clay with layers of leaf duff and is on the alkaline side.
The plant itself is only about 15" to 18" tall. I apologize for the blurry images, the breeze was blowing and these are the best I could get.
flower is about 1 1/2" diameter