William Harrison Lott, Jr. born Dallas County per Texas Birth Index.
William Harrison Lott WWI Draft Reg 1917, Delta County; born 31 Aug 1894 at Caddo Mills. Married, wife's name not shown.
Brother Tom born Hunt County. Brother John born Delta County.
1910 census lists Harrison Lott in Lamar with parents James G. and Nancy Jane. 3 brothers and 2 sisters.
James born Massachusetts. Nancy born Alabama.
1920 census has J.G. and Jane in Lamar with 3 youngest kids.
James George Lott; 17 Apr 1863 - 24 Apr 1934
Nancy Jane Bush; 29 Apr 1876 - 17 Jul 1958
There are a couple of trees online for this family. One has a photo and scanned death certs for J.G. and Jane.
There seem to be more trees tracing W.H.'s brother John Jewel Lott.
You can probably find more records once you know about where to look. I hope these will give you a start.