John Donohew’s online GEDCOM10 shows Mary’s middle name as “Thomas”.

Her death certificate records Mary Donahue Corsthwait, age 57, born in 1856 in Rowan Co., Ky, died 27 Sep 1913 in Morehead, Rowan Co., Ky, marital status “single had been married”, father Alford Donahue, mother’s maiden name Mar(scribbled out y) Donahue, both born in Rowan Co., Ky, cause of death “don’t know, never saw her sent med one or two times”, informant blank, burial info fields blank, with “(no permit granted)” noted in the bottom margin.

She was listed as Mary age 7 in 1850 and Mary L. age 17 in 1860, so despite the great variance in later records, the early ones are consistent with a birthdate in late 1842 or early 1843.

In the 1910 census she was recorded as Anna Crosthwait, age 65, mother-in-law, widowed, with her daughter Lou and Lou’s second husband Alex Bradley. She also signed the consent note for Lou’s first marriage, to Davis Turner, as Mrs. Ann Crosthwait. Those are the only two records I know of that show her name as Ann or Anna. It may be that her middle name was Luanna, or that she had three names, such as Mary Anna Louisa.

1870 census of Rowan Co., Ky, Pearce precinct, enumerated 18 June, records on p. 125B as family #58:
Crosthwaite, Owen, 37, farmer, Ky; Mary, 26, Ky; Louisa, 7/12, born Dec. All born in Ky.

The preceding household is that of Aaron and Frances [Piersall] Crosthwaite.

1880 census of Rowan Co., Ky, Pearce precinct, enumerated 1 June, lists on p. 27 as family #238:
Crosthwait, Owen, 40, farmer, b. SC SC SC; Mary, 35, wife, b. Ky Ky Ky; Louisa, 13, dau; Walker, 10, son; Owen, 5, son; Minnie, 9/12, dau, b. Aug. All children born Ky Sc Ky.

Louisa should be only 10, and Walker only 8. In later records Louisa would often report her age as if she were born about 1864 instead of 1869.