Individual Details

In 1900, Mary seemed to not be living with Archibald. She was in Reidsville, Dist 81, Rockingham Co NC, Hh 140
Mary E. Walters [she is marked B as the household before her, but that was obviously an error - the children were marked W) Born July 1845, age 54, married for 33 years, 4 children. Born in NC as were her parents.
Edward (Edmund) A., son, b. Sep 1873, age 26, single. Born Virginia, father b. Virginia, mother b. NC., traveling salesman, tobacco
Margaret, dau, b. May 1884, age 16, b. NC, father b. VA, mother b. NC.

I could not find Mary in 1910. There is a Mary Walters listed as an inmate at the Eastern State Hospital in Williamsburg, Virginia, age 67 [Mary was 65], b. Virginia, her parents b. VA. [This is a mental health care facility founded in 1773]
I also considered the possibility that there was a divorce and Mary Elizabeth remarried but I couldn't locate in Rockingham in 1910, any married Mary of the appropriate age that had been married only a short time.

Son Robert's gravestone lists his mother as Mary Elizabeth Richardson.

Her gravestone states:
Mary Elizabeth,
Daughter of Robert Payne Richardson
and Elizabeth Wright
Wife of Archibald Edmund Walters
Jul 25, 1845 - Nov 29, 1916

Her stone, that of Archibald's and sons Robert & Azariah, are all matching. It would be interesting to know when they stones were placed. Azariah died as late as 1961, so it would be fairly certain the stones were not placed at the time of the death of Mary Elizabeth & Archibald.

Birth	25 Jul 1845	Virginia
Marriage	18 Mar 1868	Rockingham County, North Carolina - Archibald Edmund Walters
Death	29 Nov 1916

Spouse	Archibald Edmund Walters (1842 - 1919)
Child	Robert Payne Walters (1869 - 1909)
Child	Azariah Graves Walters (1871 - 1961)
Child	Edmund Richardson Walters (1873 - 1958)
Child	Margaret Patton Walters (1884 - 1905)

Father	Robert Payne Richardson (1820 - 1909)
Mother	Elizabeth Newton Wright (1820 - 1848)
Sibling	Sallie A. Richardson (1843 - 1869)
Sibling	Margaret L. Richardson (1847 - )