Carlene: It may be that we have a match if we compare a few dates and relatives. Because of this unusual name, and the closeness of dates between what I have and what you have, it is reasonable to believe we are talking about the same ancestor.
Mariah E. ENOS First appears in the 1860 (taken 30 June) census of Rhea County TN in the family of William ENUS (Enos) L27, D215, F215. Mariah is listed as a 7 year old who was born in the state of IL (which indicated she would have been born in 1852 if your month and day is correct and my math is as well).
This information was likely provided by her stepmother Mary Eliza BARNETT, the second wife of her father William A. ENOS, born in Blount Cnty TN, c. 1826, second child and first son of Thomas ENOS b. 1803 SC and Barbara JACOBS b. 1805 NC, mar. 17Apr1823.
The mother of Mariah E. ENOS was Lucinda BYERLY, b. c. 1826, d. 1856 Rhea Cnty TN, perhaps died in childbirth or shortly thereafter. The siblings of Mariah were Melissa A. b. c. 1848 Knox Cnty TN, Mikel (Michael) R. b. 1849 Knox Cnty, Margaret S. b. c. 1849, Barbary b. c. 1854 IL and Lucinda, b. c. 1856.
William A. ENOS and Mary Eliza BARNETT, b. c. 1840, TN were married 04Nov1856 in Rhea Cnty TN. Of that marriage seven children were born including James Thomas, William F., Mary Eliza, Airiebelle(Sobrina), Martha, all in TN and Samuel H. and Hugh M. in Alvarado TX. This information is from The History of Johnson County Texas, Family 251.
I suspect the person you refer to in your post as "My Gggrandmother Enos' brother, W. A. Enos 10-22-1821 9-28-1907" is her father instead. The above 'History' states that "The (combined) Enos family started to Texas in 1871 by way of Little Rock AR. Four of the oldest girls remained in Arkansas". Mary Eliza ENOS "died c. 1810 and is buried in Ash Creek Cemetery, Azle TX and "William went back to Arkansas to visit his older daughters and died (there) around 1912".
This latter information fits very nicely and I have much supporting information if you like. I do not believe the information from the "History" to be completely accurate. Please let me know of your sources if you have a conflict of info with mine.
Mariah E. ENOS was likely born in Macoupin County IL although I have not found supporting evidence. Many of Williams younger brothers moved there shortly before and after 1860. Interestingly enough William A. ENOS fought for the South while his brothers fought for the North and throughout his lifetime he hated Yankees.