1900 Census, Wilkinson County, MS has

Seaberry, Thornton born Oct 1854, 45 MS MS MS
So I probably misread the 35 in 1910 and it should have been 55

with him were:

Stafford, Francis No relation, female, June 1851, 49 LA LA LA
Seaburry, Wm, son June 1888 12 MS MS LA
--------, Mathilda, Daughter May 1889 11 MS MS LA
--------, Murdey, dau June 1891 (looks like 9 written over to MS MS LA
--------, Thornton, son aug 1894 5 MS MS LA
--------, Phyllis dau Aug 1894 5 MS MS LA
--------, Ford son sept 1897 2 MS MS LA
--------, Emilie dau Nov 1879 20 MS MS LA

so it would appear that Thornton & Phyllis were twins, and that the mother of the children was Francis Stafford, since all the children are recorded as mother born in LA

Same census page had a

Seaburry, Asaring, age 32, (first name questionable) living with a Hollands family

There was also a Sim Seaburry(46) with sons Sim 17 Robt (14)and nephew William Andrews (6)

Sim would be the right age to be Thornton Senior's brother, but that is just speculation at this time.