William M Slade married Mary Lucinda Andreu on April 21, 1904 in Starke, Bradford, Florida

His marriage record, his SS death index record, his obituary and his memorial card has the middle initial of M. His son's Avory and Vernon list his middle name as M on their WWII registration cards. His tombstone has S, I'm told it's for Schuyler/Skyler. He was called "Bill".

Obituary:
WILLIAM M. SLADE, 85, lifelong resident of Bradford County, died Sunday afternoon following a sudden illness. Born in Bradford County on Sept. 2, 1880, he was the son of the late William and Elizabeth (Thomas) Slade. He was a retired farmer and a member of the Hampton Baptist Church.
Surviving is wife, Mary Lucinda Andreu Slade, of Hampton; six daughters, Mrs. Elvie Rigdon and Mrs. Jessie Mae Willis, both of Hampton; Mrs. Martha Hendry of Jacksonville; Mrs. Eva Allen, Palatka; Mrs. Alla Mae Schuppert, Fort Lauderdale; and Mrs. Myrtice Wallace, Miami; four sons, Lester, J. V., and Truby Slade, all of Hampton, and Avory Slade of Maxville; 27 grandchildren and 15 great-grandchildren.
Funeral services were held at 2 p. m. Wednesday, Jan. 5, at the graveside in Santa Fe Cemetery near Hampton with Rev. Paul Estes officiating. Interment was in the family plot under direction of DeWitt C. Jones Funeral Home of Starke.
Active pallbearers were Otto Hicks, Sr., Lonnie Melton, K. D. Watterson, Hazel Perry, Verdie Salter, and William Carter.
Bradford County Telegraph, Starke, Florida, January 6, 1966

1910 Hampton, Bradford, Florida, USA
William Slade Jr 32 Head
Cindie Slade 24 Wife
Elva Slade 3 Daughter
Vernon Slade 8 months Son
Lex Andreu 21 Boarder

1920 Hampton, Bradford, Florida
William Slade 39 Head
Mary L Slade 31 Wife
Elva Slade 13 Daughter
Vernon Slade 10 Son
Lester Slade 8 Son
Mary E Slade 7 Daughter
Eva L Slade 6 Daughter
Martha E Slade 3 Daughter
Alla M Slade 0 Daughter