This is the Standing Rock Hill Historic Site, south of Kathryn and west of Enderlin, just up the hill from Little Yellowstone Park, right off Highway 46. It is also just a short drive from Jensen Cabin at Wadeson Park. Standing Rock Hill Historic Site consists of four Native American burial mounds, the largest of which is marked with the small standing rock shown below.
There is a fairly serious grade up a minimally maintained road to get to the parking lot at the top of the hill, but in dry conditions, you shouldn’t have any trouble in the typical car. Read more about it here.
Photos by Troy, copyright Sonic Tremor Media LLC