Thornton was there in Wilkinson CO in 1880. He is listed as

Seaberry, Thornton B M 24 Single MS MS MS

Ancestry has him indexed as Teaberry.....if you want to check the originals

in 1880 there is also a 2 year old Emily Seaberry living with
Jones, Mary(59) and listed as granddaughter --- this could be Thornton's daughter Emilie as listed in 1900

1870

1870 had 11 white Seaberrys living in Scott Co, but no thornton, and no black seaburry/Seaberry -- any spelling listed in MS

What looks like it could be your people is indexed as
Thornton Sibinng

The last name is difficult to make out, but could be Sibirry or Sibring --- spelling was never reliable

S????, Peter 55 MS
-----, Emily 46 MS
-----, Lina/Sina 19
-----, Thornton 14
------, Susan 12
------, Asarine 5
------, Ida 1

These look likely, especially since Thornton named his daughetr Emily