When it comes to Isaac Jones it appears that mystery would serve as bookends for Isaac's life. As is somewhat the case with Isaac's early life and place of origin, his final resting place also remains a relative mystery to this day. Having spent time in Calloway County and having actually located his homestead, I would definitely narrow it down to one of three locations: Palestine Church Cemetery, the Morris Cemetery, or the Jeffrey Cemetery.
Palestine Church Cemetery, Calloway County, KY
(more unmarked graves than you could shake a stick at)
I'll start with the one that I personally think is the least likely, yet funny enough would seem the most logical location, Palestine Church Cemetery. Despite the earliest grave marker with an inscription only dating back to 1850, the cemetery had been in use since 1825. Many of the other markers dating back to the 1850's are either toppled or broken, so it's entirely possible that Isaac's grave could have fallen victim to the same. Having personally located and photographed upwards of 500 graves through the Find A Grave website, I know all too well how quick and thorough the grass can be when reclaiming a toppled headstone. Evidence in this cemetery, as well as other cemeteries in the surrounding area, suggests that professional headstones were obtainable and in common use many years prior to Isaac's death. Taking this into account along with Isaac's substantial personal wealth at his time of death, the notion that his grave is marked with a common field stone seems unlikely. Despite Isaac most likely being involved with Palestine Church at some level and him living a little ways to the south of the church, I don't know why he would opt to be buried at Palestine when evidence suggests people were being buried on his own property possibly even prior to his own death. This cemetery has come to be known as the Morris Cemetery.
Morris Cemetery, Calloway County, KY
The Morris Cemetery is located on privately owned land under a small grove of trees at the edge of a cow pasture on the land that Isaac left to Kesiah, which she in turn sold to William Hardy in early 1851. Although there is evidence of several unmarked graves, there are only two with actual headstones. Neither of the stones continues to mark their respective graves, and the owner of the land had told me that they had only discovered them upon hitting them with a tractor while cutting the grass not long after buying the property. The stones had long been toppled by the cows as they used the area for shade. The first of the markers belongs to Isaac's stepdaughter Lucinda Morris who had died on November 3, 1850. If Isaac did in fact die in early 1851, why wouldn't he be buried on his own land as was his stepdaughter? The other marker belongs to Thomy Hardy who had died on April 13, 1854 and was the 5 month old son of William and Sarah Hardy. Really the only thing that makes me believe that Isaac wouldn't be buried in this location is the existence of the Jeffrey Cemetery.
Jeffrey Cemetery, Calloway County, KY
(grave of Joshua Douglas Jones in the foreground.)
Located off of Roosevelt Road, the Jeffrey Cemetery seems to be the most likely location for the final resting place of Isaac Jones. The cemetery is located on the piece of land purchased from the state of Kentucky in 1835 by John Jeffrey which he later signed over to Isaac Jones in 1836. Of the 179 graves with existing headstones in the cemetery, there are five with inscriptions that predate Isaac's death in 1851. The oldest marker with an inscription belongs to a child named Lewis J. Peter who was a great grandson of Isaac through his son Burrel's daughter, Jeannette. The other four graves mentioned are also for children, all being great grandchildren of Isaac either through his son Burrel or his son Joshua Douglas. A detailed examination of the cemetery actually shows that as far as markers with inscriptions go, they all belong to children, with the first adult marker with an inscription not showing up until 1873. With this being said, one gets the impression that the family as a whole may have seen a "proper" headstone as an unnecessary expense when you take into account that Isaac, his daughters Alvina, Lydia, and Jane, and his son-in-laws Bowen Whitlock and William Jeffrey all died prior to 1873, lived in the immediate area, and have yet to have their graves located. These individuals may account for the numerous unmarked graves in the cemetery or the graves marked solely with plain field stones. Although Isaac's son Joshua and his son-in-law John Jeffrey are also buried in this cemetery and have nice markers with inscriptions, it may be that these headstones were purchased and placed after the fact by their descendants. This scenario becomes even more likely when you consider that John Jeffrey and his second wife Tennessee both have nice inscribed markers, yet his first wife Jane does not. With it's close proximity to Isaac's home and the sheer number of his descendants that are buried there, it would seem to me that the Jeffrey Cemetery would be Isaac Jones' most likely burial location.