I haven't found anything. It's possible because John was considered mulatto, that he is buried in a "Black" cemetery. At the time he was living, records for black people were not well kept. Chances are he is buried in such a cemetery in Wisconsin. Maybe Lillie is there as well although it is my understanding she may have spent her last few years in Wisconsin so she could be in Wisconsin.
His & Lillie's daughter Maybelle, is buried in the small cemetery of Grace Lutheran Church in West Sweden.