Boyd, William - Richmond County GA, 1797, Waggoner District
Waggoner, Thomas - Richmond County GA, 1797, Waggoner District

A further search of early Georgia tax records revealed no other Waggoner/Wagners and Boyds living in the same County in about 1799/1800 when Robert and Nancy were married.  (Note: it is also not known if Robert and Nancy were married in Georgia, however, since their first child was born in Georgia, we are making this assumption.)

In 1790 Thomas and John Waggoner owned property in Richmond Co GA and so did a John Boyd.  Details are not available so we don't know their ages. 

In 1820 a William Boyd was in Richmond Co, GA along with John Boyd (Note: By 1812 Robert and Nancy were in Cooper Co MO.  They and their son Robert were the only Boyds indexed in 1830 Cooper Co.  1820 Missouri census is not available)

Census Analysis:
1820 Census - Richmond Co GA:
John Boyd 1820 (Males: 2 age 0-10, 1 over age 45) - born before 1775
William Boyd 1820 (Age 26-45) - born between 1775 and 1794
Neither of them are indexed in Richmond Co GA in 1830

Richmond Co GA Boyd Marriages:
BOYD, Elizabeth JONES, Thomas 24 Mar 1792 Richmond
BOYD, Elizabeth SILIVAN, John 23 Oct 1806 Richmond
BOYD, Elizabeth HUESTIS, Moses B. 31 Mar 1824 Richmond
BOYD, John CANE, Eliza 02 Jun 1807 Richmond
BOYD, Sarah WATSON, George 10 Mar 1824 Richmond
BOYD, Thomas CRUTCHFIELD, Betsy 01 Aug 1805 Richmond
BOYD, William COLLINS, Sarah 28 Dec 1812 Richmond

Migration of Robert and Nancy based on birth locations of children:
1801 - Georgia
1803 - Tennessee
1809 - Tennessee or Missouri
1811 - Tennessee or Missouri
1812 - Cooper Co, Missouri
1816 - New Madrid Co, Missouri
1820 - Cooper Co, Missouri
1824 - Cooper Co, Missouri or Kentucky

Note: Although some records indicate that Nancy, Robert Jr and Matilda Boyd may have been born in Tennessee, there were no Robert Boyds indexed in Tennessee Tax Records or Early Census Records between 1803 and 1811.

It is possible that John or one of his relatives was a minister:

Early Chronicles of Richmond Co, GA
Competition between the Sandwiches and the Lubbocks on the pages of the Chronicle continues in the spring of 1795, with both advertising in the Chronicle of March 14, March 21, March 28 and April 4,. On April 11 a competitor EDMOND WALSH appears, who claims to have already met with encouragement as a teacher of children, and announces on April 11, 1795, that he is setting up a new school in the back part of Mr Edwards’ lot, opposite the house occupied by the reverend parson Boyd.

Earliest Record Found of Boyd Surname in Georgia:
A List of the Early Settlers of Georgia, Part II: Persons Who Went from Europe to Georgia on Their Own Account, Page 65:
A land grant of 500 acres was granted to Thomas Boyd in Georgia in 1736

Clues about the Richmond Co GA Boyd Family:
It is possible that some of the Richmond Co GA Boyds were from Chester Co, SC:
Jane Boyd b 12 Nov 1805 Chester Co, SC
death: 12 May 1881 Burke Co, GA
married: 14 Feb 1836 Richmond Co., GA
Rev Mark Lively
birth: 27 Feb 1791 Burke Co., GA
death: 31 Jan 1852 Burke Co., GA
son of Rev Matthew Lively and Elizabeth Odom (Odin)
Source: Rootsweb.com

Note:  Since the above Jane Boyd was born in 1805 in South Carolina, it is unlikely she was related to the John and William Boyd who were in Richmond Co GA by 1790, but it is possible.

Interpretation:
It appears that John Boyd was probably the father of William Boyd.  Since there are no census records for Georgia prior to 1820 we can't determine if a Robert Boyd was in Richmond Co GA.  We know Robert and Nancy moved to Missouri no later than 1812.  It is possible that John Boyd was also the father of Robert.

Waggoner, Thomas - Richmond County GA, 1797, Waggoner District
Boyd, William - Richmond County GA, 1797, Waggoner District

In 1790 Thomas and John Waggoner owned property in Richmond Co GA and so did a John Boyd.  Details are not available so we don't know their ages. 

Earliest Record Found of Wagner Surname in Georgia:
Samuel Wagner settled at Hampstead GA. He died without heir male or female and next relations had lease to sell the lot. Dead 1738.