Rowan Co. death records on LDS microfilm #216,839 list death on 15 May 1861 of Mordecai Pearce, 71, born Fayette Co., name of parents unknown, cause of death unknown. Note that the place of birth is not inconsistent with the census records which say "Virginia", since in the late 1780's Fayette Co. (and all of present-day Kentucky) was part of Virginia.

Rowan Co. will book A, p. 1, records will of Mordecai Pearce, dated 30 April 1861, which gives to his wife Mary Pearce all household goods and the farm on which he lives, to his "lawful heirs" (presumably his children, but not so described) Mary Ann Gooden, Jonathan Pearce, George W. Pearce, Deborah Utterback, Strother Pearce, Green B. Pearce heirs, Martha Nickell, and W. P. Pearce $1 each, the remainder of the estate to be divided between his grandchildren Martha Pearce and Henry Sandford Pearce, heirs of W. P. Pearce. Executor John Evans, witnesses John W. Ellington and John A. Evans. Recorded 27 May 1861.

(The two grandchildren who inherited under this will were only 4 and 3 at the time, Martha being born July 1856 and Henry in April 1858.)

1830 census of Bath Co., Ky, p. 198, line 25:
Mordica Pierce, 2 m < 5, 1 m 5-9, 1 m 10-14, 1 m 15-19, 1 m 40-49, 1 f < 5, 1 f 5-9, 1 f 30-39.

1850 census of Morgan Co., Kentucky, p. 105, records as family #252:
Mordeica Pearce, 63, farmer, b. Va; Anna, 58, b. Maryland; Martha, 19, b. Ky; Jane Ferand, 15, b. Ky. [“Jane” is probably Winnie Jane Ferrand who married Mordecai & Anna’s son Strother. She is most likely a niece or other relative of Anna. In the 1900 census, Winnie gave her mother’s place of birth as Maryland. She wouldn’t be a daughter of Anna, though, because Mordecai and Anna were married in 1819, and because Winnie married their son Strother.]

1860 census of Rowan Co., Kentucky, taken June, lists as family #112:
Mortica Pierce, 72, b. Va; Mary, 39, b. Ky; Alexander Harmon, 14, b. Ky.

I have not yet found a marriage record for Mordecai and Sarah. Her name is from the birth record of their son Jonathan.