If I remember correctly, you said his wife was Mary Mason. Could she have been also known as Margaret? I know Margaret is frequently found as Peggy; could her name have been Mary Margaret? The reason I ask is that the only George B. I can find close in age is:

1850 United States Federal Census
Name: George B Jackson
Age: 26
Estimated Birth Year: abt 1824
Birth Place: Virginia
Gender: Male
Home in 1850(City,County,State): District 10, Shelby, Tennessee
Household Members: Name Age
Robt W Smith 33 Farmer b. Va
Ann Smith 29 wife b.Va
Edward Smith 11 m b.VA
John Smith 9 m b. Va
Marian Smith 6 m b. VA
Robt Smith 1 m b. Tn
S M Oliver 50 m no occupation b. Va
Julia Oliver 33 f b. Va
George B Jackson 26 m farmer b. VA
Margaret Jackson 26 f b. Va
Richard Graves 21 m b. Va
Mary J Graves 19 f b. Va

In 1850 there were several others:
George B. Jackson age 35 and his son George Jackson age 12 living in the Norther Division, Brunswick, Virginia which would be Southwestern Virgina down near the NC border.

A John Jackson age 42 and his son George B. Jackson age 3 living in Nansemond, Virginia.

The George B. Jackson listed in the 1850 Federal Census is probably:
Virginia Marriages, 1740-1850
Groom Name: GEORGE B. JACKSON
Bride Name: MARGARET F. GRAVES
Marriage Date: 24 Nov 1844
County: Sussex
State: Virginia

The one livign in Brunswick is:
Virginia Marriages, 1740-1850
Groom Name: GEORGE B. JACKSON
Bride Name: SUSANNA S. NOBLE
Marriage Date: 17 Nov 1836
County: Brunswick
State: Virginia

George B Jackson
Born: abt 1815 Brunswick, Virginia
Died: abt 1883 Dinwiddie, Virginia
Susannah Noble
Born: abt 1810
Died: abt 1840 in Dinwiddie, Virginia

George B Jackson
Birth: 19 Oct 1823
,,Virginia
Death: 17 Dec 1871
Spouse & Children
Margaret F. Graves
1825 – 1871
Franklin E. Jackson
1853 – 1853
Mary Gilliam Mason
1840 – 1930
Margaret L Jackson
1855 – 1896
William Henry Jackson
1857 – 1929
George Robert Jackson
1859 – 1879
Lucius Emmett Jackson
1861 – 1927
Ida Virginia Jackson
1864 – 1928
Walter N Jackson
1867 – 1948
Susan Rebacca Jackson
1869 – 1900
Mary Ann Jackson
1872 – 1877

Name: George Jackson
a representative from Virginia, served in the fifth congress.

Name: John George Jackson
born in Clarksburg, Harrison county, Virginia, in 1774; received an English training, and became a civil engineer; appointed surveyor of public lands of what is now the state of Ohio in 1793; member of the Virginia house of delegates, 1797-1801; elected as a Republican to the eighth, and to the three succeeding congresses, and served from March 4, 1803, until 1810, when he resigned; again state representative, 1811-1812; chosen brigadier-general of militia; re-elected as a Democrat to the thirteenth and fourteenth congresses (March 4, 1813-March 3, 1817); declined a re-election to the fifteenth congress; appointed United States district judge for the western district of Virginia in 1819, and served until his death in Clarksburg, Virginia, March 29, 1825.

JR