Johnson Family 1870's

I am searching for information on Carroll and Mary Johnson. Mary was a widow living in Green County listed on the 1870 census with son's Richard and Jacob living with her at that time.
I believe this could be the family of Carroll and Mary [Maxwell] Johnson.
Carroll died between 1860 and 1870. My Mary died abt. 1908.
Can any one tell me where they are buried or if this is not my line?
If this is my Johnson's Mary may have moved from Green County before her death. I think Carroll may have died there. Any information about place of death and buriel would be great.
Also listed on the 1870 census were their son Van and his wife Elizabeth living two spaces past Mary. Information on any of these families would be very appreciated. Thanks Goldie.