Spoke to a Ranger. These are a native, but at least some in the vicinity of the Jenny Lake visitor center were planted as part of a restoration project. I noted 2 plants blooming today near the visitor center. No others observed further away from visitor center on near by trails. There are only 5 observations on iNat for Paeonia brownii in Teton County. All are in the area of Jenny Lake. It makes me wonder whether there would be any at all absent human intervention.
Two-grooved milkvetch abundant on former and current Wyoming big sagebrush steppe on the northeast portion of the Crazy D Ranch, southeast of Melville, Sweet Grass County, Montana.