Re: Obit lookup
Well we can't look up her obituary until we find where and when she died.
This is a very elusive family and I found nothing more than you did. I searched the Oregon Historical Archives but nothing there for any of the Boyce family.
You can request this information from the Linn Genealogical Society, rootsweb.ancestry.com/~orlinngs/ . She could have divorced William too.
You can also contact the Sweet Home Genealogical Society, shgenealogy.com/ . Hopefully one or the other will have more info about the family and Maria in particular. Successful Searching!