My name is Greg Lessley and my grandfather was William Ware Lessley who was born 1848 in Shiloh Illinois. He later moved to Lafayette La where he practiced medicene. He died in 1928 and is buried in Protestant cmetary. His parents were Alexander and Mary Scot Lessley. Alexander moved to Shiloh from South Carolina. I am guessing he was born 1790 because the 1850 Washington County Illinois census shows him to be 60.He had a 24 year-old-son born in Shiloh so that means he would have made his move before 1826.
I know we are talking about two different William's but hope in your quest you may have found something helpful.
By the way, The last name was Lesley in the 1850 census and was Lessley in the 1870 census.