Oh what a challenge you have presented.
Not going in any order, but presenting what I have found.
As mentioned in your posting, I found Littleberry in the 1850,1860 and 1870 Bedford Va census, with various spellings.
I checked the 1790 and 1800 Va census. No Fergursons or any spellings in Va
1810 though did come through with 11 differnet locales in Va but all Fergusons.
Charlotte Va.. Frances
Buckingham Va.. John
Bedford Va ... Joseph
Bedford... John Farquran
now, what I find in 1820 in Chesterfield, Va are 5 Fergusons
what is even better is there is one Littleberry age 45 with a son of 25
now we know thisis not your littleberry.. but perhaps grandson./namesake to the 25 yr old.. even though your Littleberry shows 1810 as his dob. I though have found his date as late as 1811
so, in 1820 in Chesterfield Co. Va.. there is Littleberry. age 45
William with a 15 yr od son
Moses who is 25
James witha son under 10 and he age 45
and William H. with sons 10 and under, in the 15 yrs and two sons at 25
This 1810 littleberry would have been born in 1775
sounds good enough to be your litteberry's father, yet no son is listed in the 1820 census for under ten....
So, perhaps your Littleberry is William H's son?
This is ore than you had.. hope it has been of help.
The spellings of Forgueran/Forgerson/Farquevoan and Farquevoan
are understood by the the dialect of the western part of Va.
I hope this is of help to you.
Please let me know of what you think and possibly find.