These are also known as grass pinks. I have heard these or a related species is from where the domestic carnation was developed.
I looked around for the butterfly pollinators but only saw the small flies seen on the edge of the pedals.
When we got to our turn-around-point I saw another trillium and snapped a pic. As I looked around I noticed more flowering trillium and was very surprised to see 30 to 40 in bloom not very far from where I stood. That is be for the greatest population I have ever seen.
As we were walking we kept seeing these in bloom so I took a few observations.
These plants were in a creek bed standing about three feet high and very sticky.
Pretty fuzzy pic, but it is the best I got.