The Gravestone mentions other family members, which may help you to identify whether they are "yours". Also it is a Tonna (Neath) family:
In memory of William, son of Daniel and Margaret Jones, from Tonna
who died May 23rd 1882, age 3 years
.......
Also baby Thomas their son, who died 11th March 1895, age 8 years old (think this should be 3)
Also John, their son, who died 19th January 1887, age 5 weeks old.
Also the above Margaret Jones who died 11th December 1909, age 50
....
Also the above Daniel Jones, who died 24th january 1915, age 72
The stone is too worn to say whether it is 3 or 8

Modified - Having looked at it again, I think it's a 9, and there is a Neath death in the relevant quarter with age 9
