On 1851 census living with Lucy and Clayborn Overstreet are Nancy, 18 and Delilah Atwood, 20.
Lucy's sisters? Both born in US.
I also checked all the US census on familysearch but no luck with any of your Atwood names.
1881 census says Lucy was born Alabama.
1891 census gives George 17, and Joseph 15.
Also says they were Mormon. Have you checked with their records?
If they were born in Kentucky and Alabama I doubt if they would have been included in early US census.
On an Albert Overstreet's marriage rego it says his mother is Hattie Lawson, father Claborn Overstreet. He is aged 23 so born c 1888. On his death rego it gives father as Edmund J Overstreet and mother Hattie Lawson so I guess he isn't your Albert.http://www.ckblackhistoricalsociety.org
There's several articles on Google regarding black history in Chatham and surrounding areas.