Authentic Historic tombstone site is actually in the Attica Cemetery, Harper County, Kansas.  And this ole' cavalryman died 128 years ago!*

 Snope says TRUE:

ORIGINS:   The short answer to the standard “Are these real?” question is that the pictures displayed above are indeed real, photographs of a marker at the grave of Nathaniel Grigsby, who died in 1890 and was interred at the Attica Cemetery in Attica, Kansas.

The longer answer involves explaining what might have driven Nathaniel Grigsby to request that the following epitaph be placed upon his grave marker-