Hello, You must be the man who has so honored his family by replacing all the old and aged monuments/markers in Alta Vista cemetery in Gainesville, GA.
I've researched the Roberts family for about 13 yrs as well as all of their extended families. I don't have much on Robert Smith other than census and his death during the War (1827-1864) & marriage to Winnie Elmina Roberts, dtr of Cornelius b. 1809 and Dollie unknown (not Van Buren).
I have been much interested in one of their children, A R (Alphus "Alf") Smith after finding many yrs ago information from Memoirs of Georgia - perhaps Memoirs of Hall Co GA - that he entered Emory at Oxford College in 1883 - became clerk of Superior Court in 1885 (Hall County I think) and was re-elected to 6 successive terms, etc.,etc.
I don't know what happened to him - he was quite accomplished. Based on what I've learned of Alpha - Alphus, I have always been interested in learning more about him/his siblings.
Winnie's mother Dollie's name may never be known but it was not Van Buren. A person new to genealogy posted that based on Cornelius and Dollie having named a son Martin Van Buren Roberts - thinking Van Buren might have been Dollie's family name. It's more likely he was named for President Martin Van Buren. Once this Van Buren surname was added online to Dollie, it spread quickly among ancestry folk. One of Cornelius' brothers also named a son Martin Van Buren Roberts - I scarcely think he would honor a sister in law by in that way - it would be highly suspect!
Also, Cornelius was not married to Mary Porter. Mary Porter was briefly married to Cornelius brother, Hardin Roberts (1814, Columbia SC to 1884, Forsyth County, GA). The divorce was granted to Hardin - and in 1854 Mary Porter was officially granted permission to remarry. Oh yes, there are lots and lots of Hardin(en)s in this Roberts line.
Also, when you see online that Cornelius 1809 was Cornelius Harden Roberts, I don't believe it. Now why, when Cornelius' parents picked out names would they have named him Cornelius Hardin, then later named another child Hardin?
And, it is this Hardin b 1814 who was known as Hardin, Jr., as evidenced in Hall County GA records.
This mixup occurs no doubt because Cornelius named one of his own sons, Cornelius Hardin Roberts(who was never known as a Jr). This son was in the Civil War - and folks have mixed up the 2. Cornelius 1809 stayed home and farmed during the war. Most seem to think 1809 was in the war but he was not - it was his son b 1845.
You asked about Smith - I gave you little Smith and lots of Roberts information. I wish I had as much information about the Smith family as the Roberts family.