William Lay was living at home with his parents Daniel B. and Lilly M. Lay at the time of the 1930 census of Wilson Co TX. He was mentioned as a surviving son in the obituaries of his father (1949) and his mother (1953). The dates of birth and death listed here are the taken from the SSDI a William Lay who died in San Antonio in Nov 1967. The date of birth given by SSDI agrees pretty well with what was listed in the 1900 census (Mar 1898).
It is not known if William Lay married or had children. There are two births registered in Bexar Co TX to a father named William Lay, and at approximately the right time to be his children:
1Name: Barbara Larue Lay
Date of Birth: 21 Feb 1928
Gender: Female
Birth County: Bexar
Father's Name: William Lay
Mother's Name: Jewell Dayton
Name: Evelyn Lay
Date of Birth: 8 Mar 1932
Gender: Female
Birth County: Bexar
Father's Name: William Lay
Mother's Name: Jewel Dayton
However, these cannot be his daughters because in 1930, William Lay, age 32, was still living at home with his parents.