1.  Jordan R. Dodd, ed.  1993.  Virginia Marriages:  Early to 1850.  Liahona Research, Orem, UT (Broderbund CD-229):

Smith, Ballard

Davis, Polly

20 Dec 1808

Greenbrier Co.

2.  AIS (Accelerated Index System) Census Index (online at Ancestry.com):

1820	Smith	Ballard	VA	Greenbrier Co.	Lewisburg	p.  83
1830	Smith	Ballard	VA	Greenbriar Co.		p. 203
1840	Smith	Ballard	VA	Greenbrier Co.	S Greenbrier	p. 229
1850	Smith	Ballard	VA	Greenbrier Co.	District 18	p. 327
1860	Smith	Ballard Sr.	WV	Greenbrier Co.	Lewisburg P.O.	p. 234
1860 Slave Schedule	Smith	Ballard	VA	Greenbrier Co.	Dist. 1	p. 248

3.  1810

4.  1820

5.  1830

6.  1840

7.  1850 Census Index/Microfilm (online at GenealogyLibrary.com):  District 18, Greenbrier Co., VA, p. 327B, 1281/1281, enumerated 14 Nov 8150 (extracted by Diana Gale Matthiesen):

Ballard Smith	67	M	Farmer	4000	Va
Mary Smith	60	F			"
Ballard Smith	26	M			"
Mary A Smith	17	F			"

Mary A. would appear to be the wife of the junior Ballard.

8.  Biographical Directory of the United States Congress (online at the Congressional web site):

SMITH, Ballard, a Representative from Virginia; born in Hanover County, Va.; served as lieutenant in the Army during the Revolutionary War; member of the State house of delegates 1810-1813; elected as a Republican to the Fourteenth, Fifteenth, and Sixteenth Congresses (March 4, 1815-March 3, 1821); again a member of the State house of delegates 1824-1826, 1836, and 1837.

If he served in the Revolutionary War, then he cannot be the Ballard SMITH who married Polly DAVIS — or has the biographer confused Ballard with his father, who was a Lt. in the Rev. War.  If Ballard served in the war, then he would have been at least in his 70s when he held office in 1837.

9.  The National Society of the Daughters of the American Revolution (online at Ancestry.com):

Vol. 160, p. 221

Mrs. Lillian Ballard Smith Starcher; DAR ID Number: 159692  Born in Charleston, W. Va.; Wife of George Columbus Starcher.  Descendant of Lieut. Francis Smith, as follows:  1. Charles Ballard Smith (1845-94) m. 1872 Mary Shelton McConihay (b. 1853).  2. Thomas Preston Smith (1811-91) m. 1843 Mary Lucy Barrett (1820-99).  3. Ballard Smith (1774-1870) m. 1808 Polly (Mary Gray) Davis (d. 1873).  4. Francis Smith m. Catherine Markham.  Francis Smith (1742-1833) served as 1st lieutenant of cavalry in the Hanover County, Virginia troops. He was born and died in Hanover County, Va.

Based on the 1850 census, Ballard was born 1782/3, which is also more reasonable given his marriage date.

10.  Lyman Chalkley.  1912.  Chronicles of the Scots-Irish Settlement in Virginia: Extracted from the Original Court Records of Augusta County, 1745-1800.  3 vols.  Commonwealth Printing Co., Rosslyn, VA (online at Ancestry.com):

CIRCUIT COURT RECORDS, SECTION "I." JUDGMENTS. page 182 William Douglass vs. Davis--O. S. 232; N. S. 82--  ... Jane, who married John Davis and is now a widow and lives in Greenbrier...  Ballard Smith, attorney-at-law, is son-in-law of Mrs. Davis, the defendant.