Left Hand Spring was a well-known watering stop on the old Chisholm Trail in present-day Blaine County, Oklahoma. The spring was named for "Left Hand", an Arapaho chief. Jesse Chisholm died there in 1868 and is buried nearby. His grave is marked with a granite historical marker.
Jesse's grave has a plaque detailing his accomplishments.
With the mention of the granite historical marker, there is nothing stopping another object from being at his grave site, especially one that has a description of his life. I think the system assumed the granite marker is the only single object at his grave.