Hydrophyllum alpestre or capitatum?
Possible herbarium specimen
Hydrophyllum is a genus of flowering plants in the waterleaf family which includes several herbaceous perennials native to North America. They include Hydrophyllum capitatum, the dwarf waterleaf or ballhead waterleaf. Its head is made of a series of five-petaled, five-stamened purple flowers. It was used as a nutritious food source by Native American peoples.