You might want to check with the State Archives in Austin, they have a state wide death index 1903-1940.It would give name of county and date of death.
1870 census Navarro Co, TX, ED 87, Sh 16 B:
Henderson, C.S., head, 39, M(1) 19 yrs, b AL, NC, NCMerchant
", Lula, wife, 39, M(1) 19 yrs, 7 ch, 6 lvg, b AL, AL, AL
", Clyde, son, 15, b TX, clerk - groceries
", Myrtle, dau, 12, b TX
", Maggie, dau, 10, b TX
", Blanch, dau, 8, b TX
", Floyd, son, 4, b TX
", Ralph, son, 5/12 b TX
I would guess the child they lost would be the one born between Blanch and Floyd.If so, it probably died between 1864 and 1870.
Note, "C.S." maybe his name was Chapman Samuel(?) You may want to look for it both ways on records.Since he was a grocery merchant,he probably owned land.I would look at land and probate records in Navarro Co, TX.Also, county tax records, when his name disappears and Lula appears, she is a widow.
In your query for Navarro Co, TX GenWeb site, you might also ask if anyonehas a county history, and would they check for this particular Henderson family.There's a good chance Samuel will be at least mentiioned, since he was a local merchant.I say this "particular" family, because there are many on the 1910 census.
Here is a "possible" match for Samuel from McKinleys, Monroe Co, AL 1880 census:
Categories: Name;Relationship to head of household; Marital Status; Gender; Race; Age; Birthplace; Occupation; Father's Birthplace; Mother's Birthplace.
A. E. HENDERSONSelfWFemaleW45ALKeeping HouseALAL
This Samuel is right age, and birth place for him and parents match 1910 census.
Happy Hunting (^_^)