Sam - I'm finding evidence that doesn't exactly match your information. I found a marriage record for John G. Strong in Copiah County to Mrs. Rebecca Jackson, 14 Mar 1854.
On the 1860 census, there is a family listed as follows:
J G Strong 30
Rebecca Strong 38
Elizabeth Jackson 14
Ellen Jackson 11
M Jackson 10
J T Jackson 20
On the 1870 census there is a family whose names were fairly well shredded by the ancestry.com transcriber as follows (my reading of the names from the actual census in parenthesis):
Jno C Stranz 40 (Jno G Strong)
Rebecca Stranz 48 (Rebecca Strong)
Mantzamang Stranz 19 (Montgomery Strong - likely Alfred Earl Montgomery Jackson)
Hugh Stranz 23 (Hugh Strong)
Bahgora Stranz 14 (This is a female - hard to read - maybe Baligona??)
Delanna Strong 68 (I read this one as Delania)

I do not find a record of Rebecca's death or her grave, but assume she must have died in the 1870's, as several family trees show that he married Nancy Ann Reed in 1880.