Almost certainly a descendant of Watkin WATKINS of Wales, who settled in Delaware/Marion Co., OH.

1.  Anon.  1966.  Marriage Index:  Ohio, 1789-1850.  Liahona Research, Orem, UT (Broderbund CD-400):  not found, except for the marriage of Ammon WATKINS to Rachel MILLER in 1826 in Clark County (see their famly group sheet).  Ammon WATKINS is a very rare name.  I know of only two: our subject and one who appears in Clark Co., OH.  The Ammon WATKINS who married Rachel MILLER in 1826 in Clark Co., OH, may be our subject, although we find Rachel WATKINS living alone with just a young daughter in the 1830 census of Clark Co.  If the two Ammon WATKINSes are the same man, he either divorced or deserted Rachel, which is unlikely, but given the difference in ages between Ammon and Jane, one would expect that he had had a prior wife — and Ammon WATKINS is a very rare name. 

3.  1840

4.  1850 Census Index/Images (online at Ancestry.com; Image #45 of 55 — indexed "Aminon"):  Marion Twp., Marion Co., OH, p. 88A/175, 317/315, enumerated 23 Jul 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):

Ammon Watkins	42	M		Farmer		Va
Jane      "	33	F				O
Priscella "	14	F				O
Olive     "	12	F				O
Amilia    "	10	F				O
Jane      "	8	F				O
Alcinda   "	3	F				O
Catharine Search	60	F				NJ
Jacob        "	28	M		Farmer		O
Charles B    "	24	M		"	1200	O
Mary Graves  "	35	F				O
Hariet Stroub	9	M				O

Ammon's given name is difficult to read.  Basically, it's a capital "A" followed by six bumps and ending in "on" — definitely not enough "bumps" to be "Amermon."  Catharine is Jane's mother; Jacob, Charles, and Mary are Jane's siblings.  Harriet STROUB is Jane's niece, d/o Samuel STROUB & Martha SEARCH, who are apparently deceased. 

5.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).  Says he is "Amermon" and she is "Harriet Jane."

6.  LDS.  Family Search: Internet Genealogy Service: Pedigree Resource File (index to CDs, online at FamilySearch.org).  Two files say he is "Amermon" and she is "Harriet Jane."

7.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).  Three files say he is "Amermon" and she is "Harriet Jane."