This is pretty interesting. These names are very close to many in my family that lived during the same period:
William Exter, Born 1847, Died 1906 (approx.) married in 1871 to Elizabeth Trenerry
Children: Samuel Henry Exter, William John Exter, Edward Exter, Annie Exter, Susan Exter
The Exters in my family originated in Cornwall, England. No idea if there's any actual relation. I live only four hours from St. Clair County, so I suppose I'm going to have to visit this cemetery one of these days.