The elder Donald Cameron died in Macoupin Co IL on 17 Sept 1894 at 80 yrs old. (*Macoupin County Enquirer 14 Aug 1895, 'The Old Settlers Memorial Roll', the always read the roll call each August at the Old Settlers Meeting taking note of the memebers who had died since the previous August 'roll call').
The Macoupin Co genealogy/historical society might have some insight into personal history. Not all the cemeteries have been 'read' and/or online yet, I've no idea which cemetery by Brushy Mound area he may have been buried in and/or if a stone still survives.
He's also mentioned in a recount of an old student of his as being her teacher in an 1929 inteview of the lady in her old age... but really more or less in passing just noting he had been her teacher in the first school building in Carlinville(the interview is about her hearing the speeches of Lincoln/Douglas in 1858 among other historical recalls, having been born in 1844...so Donald Cameron likely was her teacher in the early to mid 1850s)