I've pretty much exhausted my resources without confirming a burial location for Mattie Gupton. Oxford, NE straddles a county line, and it appears the cemetery may also be in both Furnas and Harlan counties. I've not received a reply to a request I sent to a genealogist there. I did learn that Mattie's given name was Martha and her husband, Pleasant, was a local sheriff in KY at one time. Since she died in Nampa, someone had to handle arrangements locally. I'd suggest calling Alsip Funeral Chapel to see if they have a record. There was another funeral director in Nampa, Talley Funeral Home, and I'm not sure of their years of operation, but Alsips have their records, also.
Successful searching - Mary