The LDS Ancestral File has Catharine's parents as William & Rachel (THOMPSON) WYATT.  It has Catharine's birthyear as 1829, while the birthyear calculated from her tombstone is 1823.  But no daughter of either age shows up in the household of William & Rachel (THOMPSON) WYATT in the 1840 census, and no daughter of that name or age shows up with them in the 1850 census.  Plus, William & Rachel weren't married until 1825, so if the 1823 birthyear is correct, it becomes even less possible that she's their daughter.

Malinda was almost certainly a widow when she married Jason.

1a.  D.L. Murray & N.R. Murray, compilers.  1996. Marriage Index: AR, MO, MS, TX, 1766-1981.  Marriage data from the "Hunting for Bears" collection (Broderbund CD-5):

ST CLAIR, Jason B

WILLS, Frances

22 Jun 1853

Andrew Co., MO

1b.  Jordan Dodd, ed.  1998.  Marriage Index:  Missouri, 1851-1900.  Broderbund CD-234):

Stclair, Jason

Wyatt, Catherine

28 Mar 1858

Grundy Co.

2.  Census Index:  U.S. Selected Counties, 1840 (Broderbund CD-316):  not found.

3a.  Census Index:  U.S. Selected Counties, 1850 (Broderbund CD-317):

1850	St Clair, J.	MO	Taney Co.	Prairie Twp.	p. 377
1850	Steiucler, J.	MO	St. Louis Co.	St Louis 1st Ward	p. 78

These are the only possibilities on the CD, and I really looked, both in MO and KY.

3b.  1850 Federal Census of Taney County, MO (online in the Census Archives of USGenWeb):  Prairie Twp., Taney Co., MO, p. 377A, 509/509, enumerated 7 Oct 1850 (extracted by Barbara Logan):

St. CLAIR J.	31	M	Farmer		Kentucky
St. CLAIR E.	27	F			N Carolina
St. CLAIR W.F.	3	M			Missouri
St. CLAIR S.P.	1	F			Missouri

Despite being the right age and being born in the right state, this would appear not to be our subject.  His wife should be "F.," age 32, and there should be a son, John, age 4.  Also, given where he ended up, Taney Co. (in southernmost Missouri, on the state line with Arkansas) is an unlikely location, while St. Louis is a jumping off point to the Missouri River and from there to northern counties, such as Sullivan.

3c.  1850 Census of Sullivan Co., MO (online at USGenWeb):  not found, nor any other ST. CLAIR.

4.  Census Index:  U.S. Selected Counties, 1860 (Broderbund CD-318):  no MO records on CD.

5a.  Census Index:  U.S. Selected Counties, 1870 (Broderbund CD-319):  no MO records on CD.

5b.  Family Quest Archives:  Missouri 1870 Census Index.  Heritage Quest ACD-0019:

Surname	Given name	Age	Sex	Race	Birth Place	County	Locality	Roll	Page
STCLAIR	JAMES B	51	M	W	MO	SULLIVAN	TAYLOR TWP	823	293

Obviously, Jason has been misread as James (both names have the same number of "bumps" after the "J").  He is the only ST. CLAIR in the county.

6a.  Census Index:  U.S. Selected Counties, 1880 (Broderbund CD-320):  no MO records on CD.

6b.  1880 Census Images (online at Ancestry.com:  Taylor Twp., Sullivan Co., MO, p. 185B, PN 4, SD 5, ED 200, enumerated 3 Jun 1880 (extracted by Diana Gale Matthiesen):

1800:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

1

2

3

4

5

6

8

9

10

13

14

21

24

25

26

32

33

St Clar Jason

W

M

62

/

Farmer

/

MO

KY

KY

_______ Melinda

W

F

57

Wife

/

Keeping house

KY

KY

KY

_______ John W

W

M

21

Son

/

At School

/

MO

MO

KY

_______ Flora C

W

F

18

Daughter

/

/

MO

MO

KY

7.  Veterans' Schedules:  U.S. Selected States, 1890 (Broderbund CD-131):  no MO records on CD.

8.  1900 Census Index/Microfilm (online at Genealogy.com):  Third Street, Humphreys, Bowman Twp., Sullivan Co., MO, p. 9B, SD 2, ED 147, SN 9, enumerated 15 Jun 1900 (extracted by Diana Gale Matthiesen):

1900:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	19	22	23	24	25	26	27	28
175	180	St Clair Jason B.	Head	W	M	Apr 1818	82	M	10			MO	KY	KY	Retired Farmer	Y	Y	Y	O	F	H	110
		________ Natiler? Natila?	Wife	W	F	Nov 1835	64	M	10	5	4	PA	PA	PA		Y	Y	Y

Her children had to have been by an earlier husband as they are grown and gone.

9.  Mrs. B.F. Hoover, Mrs. O.L. Livingston, Mrs. Delbert Hesler, & Cindy __?__.  1965.  Lindley Cemetery, Sullivan County, MO (online at the Grundy County MOGenWeb site; transcribed from the written record by Larry Flesher; n.b., they had the records in alphabetical order, I changed them to chronological order):

Located on the edge of Sullivan County; S15.T61N.R22W; just across border of Grundy County, Marion Township.  It is near Old Lindley, a pioneer settlement, which flourished in the early years of the county, then almost disappeared when railroads and highways missed it...
ST. CLAIR	Frances		30 Nov 1857	39y 10m 3d; wife of J.B.
	James U.		23 Feb 1861	15y 5d
	Catharine E.		29 Nov 1863	40y 8m 26d; wife of J.B.
	Nancy M.		07 Nov 1865	12y 10m 8d; dau of J.B. & F.
	Mary		02 May 1883	86y 6m 29d; wife of Jonathan
	Malinda		26 Dec 1887	64y 1m 20d; wife of Jason B
	Jason B.		15 Apr 1901	81y 11m 17d; husband of Malinda

Ten-to-one, Mary is Jason's mother.

10.  Birthdate calculated using Daisy Gambel's Birthdate Calculator.

Entered		Result
30 Nov 1857	3d 10m 39y	27 Jan 1818
23 Feb 1861	5d     15y	18 Feb 1846
29 Nov 1863	26d  8m 40y	3 Mar 1823
7 Nov 1865	8d 10m 12y	30 Dec 1852
2 May 1883	29d  6m 86y	3 Oct 1796
26 Dec 1887	20d  1m 64y	6 Nov 1823
15 Apr 1901	17d 11m 81y	29 Apr 1819
(Calculated birthdates should always be prefaced with "ca." — you can't be certain the person who calculated their age did it correctly.)

11.  LDS.  Family Search: Internet Genealogy Service:  AF - Ancestral File (online at FamilySearch.org).