1.  Jordan R. Dodd, ed.  1993.  Illinois Marriages: Early to 1850.  Liahona Research, Orem, UT (Broderbund CD-228):

Wyatt, John

Desberry, Mary Ann

12 Jul 1827

Greene Co.

2.  Census Index:  U.S. Selected Counties, 1830 (Broderbund CD-315):

Wyatt, John

IL

Greene Co.

p. 33

3.  Census Index:  U.S. Selected Counties, 1840 (Broderbund CD-316):
Can't find Mary, at least not in Greene Co., IL, or in MO.

4.  Census Index:  U.S. Selected Counties, 1850 (Broderbund CD-317):

Wyatt, Mary Ann

MO

Mercer Co.

56th Dist.

p. 400

5.  Jordan Dodd, ed.  1998.  Marriage Index:  Missouri, 1851-1900  (Broderbund CD-234):

Wiet, Mrs. Mary

Vencill, Hugh

24 Sep 1856

Grundy Co.

This looks like it might be our widow getting remarried, but I'm told she died as "Mary Wyatt," so apparently this is different widow.

6.  LDS.  Family Search: Internet Genealogy Service: International Genealogical Index (IGI).

7.  Message #160 in the Wyatt Family Genealogy Forum (online at GenForum.com).