No primary source. Secondary sources include:
"The Ancestry of Samuel, Freda, and John Warner" (1949), p.406 which says b. about 1610 Monmouthshire, England,
"Memoirs of the Leonard, Thompson, and Haskell Families" (1928) which also says born about 1610 in Monmouthshire
The former goes further and states "Solomon Leonard (Lenner, Lernardson) is said to have emigrated first to Leyden, in Holland, probably with his father whose name it is believed was Samuel. However, the name does not appear in recent lists of Pilgrims in Holland and the name Samuel may have come down from his wife's family. It is not known just when he came to New England but it was probably in 1629."
But I guess if this last claim were true, he would have his own profile in the Great Migration series.