On the 1880 Denton Co, TX census Mary is living with siblings and parents Hamton(sic) & Margaret ByrdOn the 1900 Denton Co, census Mary "Fane" is living with her Byrd siblings and widowed mother Margaret Byrd.Mary is listed as divorced.I would obtain a copy of their divorce record.More then likely there will be something in the record regarding "cause" for divorce and if he was running with outlaws that might well be covered, too.
My gr grdparents were divorced in 1904 in NM and in the divorcepapers were the papers regarding the deposition/hearing. He told about boarding the train on which she left town, and he went as far as his money would take him (and still return home), trying to talk her into returning to him and their 3 young children.She did not show up for the hearing, so we don't have her side of the story.Other witnesses gave their depositioins, too.One being gr grdpa's cousin.
Now, keep in mind, Mary was born ca 1873, so Will would have had to be some older then her to be running with Sam Bass.Denton Co, TX was Sam's stomping grounds with his "Denton Mare."Often the stories of local legends get intertwined with our own family histories.Maybe Will was on the wrong side of the law and was compared to Sam Bass by someone in the family, later the story might grow including Will in Sam's gang.I often see people saying family tradition says their ancestor was on the Trail of Tears, one look at time period and you can see they weren't even born, yet.
So, if you could get marriage and divorce records for Mary and Will and get a handle on his age, it might help clear up whether he even was the right age to have been with Sam Bass.