1a.  Family Group Sheet by Betty Ann (Matthiesen) Cogliati and her grandmother, Maude Irene (Thompson) Rose, which cites, among other things:

1b.  Monroe County, Missouri, Marriage Book A, p. 27.

1c.  Jordan R. Dodd, ed.  1993.  Missouri Marriages:  Early to 1850.  Liahona Research, Orem, UT (Broderbund CD-227):  not found.

2.  1850 Census Index/Images (online at Ancestry.com; Image #28 of 66):  District 56, Mercer Co., MO, p. 386B, 174/1, enumerated 26 Aug 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):

James H Thompson	29	M		Farmer		Kentucky
Angaline	25	F				Virginia
Sarah	7	F				Mo
Delila	5	F				do
Mercer?	4	F				do
Thomas	7/12	M				do

Living next door to Angeline's parents, Benjamin & Malinda (GAULDING) THAXTON, who are two households from Royal & Delilah (GAULDING) WILLIAM, in one directions; and, in the other direction, three households from Richard & Elizabeth (__?__) WILLIAMS. 

3.  1860 Census Images (online at Ancestry.com; Image #14 of 14):  Middlebury P.O., Washington Twp., Mercer Co., MO, p. 200, PN 100, 727/727, enumerated 19 Jun 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):

Ann Thompson	39	M				100	Virginia
Sarah   "	17	F					Missouri
Delila  "	15	F					"
Mercer  "	13	M					"
Thomas  "	11	M					"

The fact that Thomas was Angeline's last child suggests that her husband died not long after the 1850 census.  Living next door to Ann's parents, Benjamin & Malinda (GAULDING) THAXTON. 

4.  Family Quest Archives:  Missouri 1870 Census Index.  Heritage Quest ACD-0019:  Angeline is living with her second husband, Thomas REID.  Could not find Mercer. 

5.  1880 United States Census and National Index (LDS Family History Resource File: CD-ROM Library):  Angeline is still living with her second husband, Thomas REID.  Still could not find Mercer.

6.  Broderbund.  World Family Trees.  Vol. 1, Pedigree Nos. 1943, 1944, 2923.