Bet you never thought that one day you would have to know how to write a source citation for a gravestone! If you are working to find at least three sources to confirm your research results, then you will probably find a tombstone on your list at some time or another.
Evidence Explained by Elizabeth Shown Mills* makes it simple. The basic format is:
Cemetery (Location), Item, data collection info, date photographed.
Now let's assume for a moment that you didn't take the photograph yourself, but rather, found it on Find-A-Grave. The format for a reference note would be:
Find A Grave.com, digital images (http://www.findagrave.com: accessed: 12 December 2014, photograph, gravestone for Mary Jane Smith Thompson (1884-1974), Kansas City, Missouri.
See how easy it is?
Keep citing those sources!
____________________________________________*Source: Mills, Elizabeth Shown. Evidence Explained : Citing History Sources from Artifacts to Cyberspace.