I think you may have a mystery on your hands.
James Madison Stone of Company H, 24th Virginia Cavalry was born [according to the 1900 Census of Henry County, Virginia] in February 1823. At that time he was a widower, living with his son, James O. Stone (b. Dec. 1849) and daughter-in-law, Ada. Family files indicate that he was the son of Littleberry Stone. In 1846 James M. Stone married Susan Elizabeth Martin. This family appars on the 1850, 1860, 1870, 1880 and 1900 census records of Henry County, Virginia. I can't find him in the death records [volume I & II] of Henry County.
James M. Stone enlisted in the 32nd Battalion Virginia Cavalry on March 8, 1862 at Henry Courthouse (Martinsville, Va.) On September 24, 1863 the 32nd Battalion was absorbed by the 42nd Virginia Battalion and became the 24th Virginia Cavalry on June 8, 1864, serving with that designation to the end. Stone was paroled at Appomattox. He will have TWO Compiled Service Records. One in the 32nd Battalion as "J. M. Stone" and one with the 24th Virginia Cavalry. In 1997, the Virginia Regimental Histories Series published "24th Virginia Cavalry" by Darryl Holland of Henry County. See link below:
http://www.worldcat.org/oclc/37802800&tab=holdings?loc=Union+WV
The best source for information on the Stone Family is the Bassett Historical Center in Henry County, Virginia. Ms. Pat Ross and Ms. Anne Copeland of the center are two of the best research librarians in the state.
http://www.bassetthistoricalcenter.com/exhibitions.php
As luck would have it, Darryl Holland, author of the 24th Virginia Cavalry will be part of an symposium on October 4, 2008. See: http://www.myhenrycounty.com/historycorner/2008-10-04-history-symposium.pdf
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Here is the rub:
There was another "James M. Stone" who actually lived in Greenbrier County. This man was born circa 1843 and was a member of the 26th Battalion Virginia Infantry. He enlisted at Lewisburg, [West] Virginia on March 24, 1862.
The Stones as they appeared on the 1880 Census of Greenbrier County (Fort Spring District):
James M. Stone 37
Fannie Stone 38
Leonadus Stone 13
William Aurthor Stone 11
Kate Lewis Stone 10
Charles Emmet Stone 7
Willie Robertie Stone 6
Ira Blife Stone 4
Cecil Stone 2
In 1900 they lived in Cass County, Indiana.
James M Stone 56
Fannie V Stone 58
James D Stone 21
Sallie B Stone 16
Dallas P F Stone 8
By 1910, Fanny (Fannie) a widow was back in Greenbrier County.
Fanny V Stone 68
James D Stone 30
Joseph Stone 28
Blanche E Hogshead 19
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Does Stone's headstone look like: http://www.flickr.com/photos/shoelessjoe/506877047/
If it does a record of the application may be on file with:
http://www.cem.va.gov/
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I'm not trying to confuse you, but somtimes family members with good intentions order government headstones without a great deal of research. That may not be the case. The man from Henry County, Virginia may have moved to Greenbrier County. You may want to check with Jim Talbert at the Greenbrier Historical Society in Lewisburg. You may also want to check courthouse reords to see who has owned the property in the past. The other names in the graveyard may provide some clues.