Hi Terry
As Andy has mentioned, her marriage cert should be there for you to confirm Mary Ann's parents.
From the little I have seen, her Obit in 1940 gave her birth as being in Brechin in 1852. However, her census info, which was pretty consistent with birth year of c. 1854 and birth place Menmuir, would make me think this may her birth entry
https://familysearch.org/pal:/MM9.1.1/XBDX-LQQThere is another 1854 birth but this was in Montrose
https://familysearch.org/pal:/MM9.1.1/XBD5-M13I think this will be Mary in 1881 with first born William:
Alexander Morgan 24, farm servant b. Edzell, Forfarshire
Helen G Morgan 21, wife
Mary Morgan 2
Alexander Morgan 5
Mary Morgan 26, sister, Domestic Servt, b. Menmuir
William Gibb 6 Months nephew b. Brechin, Forfarshire
Address: Newbigging Cottar Ho Townhead Cottar House, Lethnot and Navar, Angus
With Andy's help, you should be able to confirm parents' details now

Monica