1.  Anon.  1966.  Marriage Index:  Ohio, 1789-1850.  Liahona Research, Orem, UT (Broderbund CD-400):

Lamb, Peter

Walters, Polly

13 Mar 1811

Fairfield Co.

2.  1820 Census Index and Digital Images (online at Ancestry.com; Image #3 of 4; extracted by Diana Gale Matthiesen):

1820

OH

Fairfield Co.

Walnut Twp.

p. 104A

Ln. 13

Peter Lamb

300110-30010-0-200

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
3 males	9 or under	1810-1820	= Peter (b. 1819) = Jacob (b. 1813) = John (b. 1812)
1 male	19-25*	1794-1801	= ?
1 male	26-44	1775-1794	= Peter (b. 1781)
3 females	9 or under	1810-1820	= Maria (b. 1821? 1820?) = Catharine (b. 1818) = Elizabeth (b. 1814)
1 female	26-44	1775-1794	= Mary (b. 1793)
2	persons engaged in agriculture
*In the 1820 Census, the third column is age class 16-18 and the fourth column is age class 16-25; therefore, any individual in column three is duplicated in column four.  By subtracting the number in column three from the number in column four, you can create an age class "19-25."

Listed one line below William LAMB, who is one line below George LAMB, and two lines above Valentine CUPP. 
 

3.  1830

4.  1840

5.  1850 Census Index/Images (online at Ancestry.com; Image #48 of 51):  Walnut Twp., Dist. 41, Fairfield Co., OH, p. 219B, 1331/1331, enumerated 6 Sep 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):

Lamb Peter	69	M		Farmer	15520	Va
"  Mary	57	F				Penn
"  Peter	29	M		"		O
"  Nancy	23	F				"
"  Eleanor	21	F				"
"  Thomas	20	M		"		"
"  Henry	17	M		"		"
"  Louisa	15	F				"

Listed next to Samuel CUPP & Magdalena WALTERS, who are next to Samuel's father, Valentine CUPP, in one direction; and, in the other direction, living next to Peter's brother, William LAMB, and his wife, Catharine CUPP, who is Valentine's daughter.. 

6.  1860 Census Images (online at Ancestry.com; Image #4 of 54):  Pleasantville P.O., Walnut Twp., Fairfield Co., OH, p. 226B, PN 186, 1360/1360, enumerated 3 Aug 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):

Peter Lamb	79	M		Farmer		2000	Va
Mary    "	68	F					Penn
Thos    "	30	M		Farmer			Ohio
Henry   "	25	M		Do	8000		Do
Louisa  "	21	F		Domestic		1200	Do
John Culp	11	M		Do			Do

Listed next to Peter's brother, William LAMB (& wife Catharine CUPP).