Well, there are a number of trees on Ancestry which show Mary as having Baker as a maiden name, but I can't find any of the attached sources which show the Baker name as her maiden name, on the contrary they show Shook or a varient spelling as her maiden name. (this includes death certificates and her marriage record to Alfred. Now on the 1880 census (which Magnus linked to) she's shown as Alfred Wilson's mother in law, which would normally mean Shook was her married name and not her maiden. But, of course she could have taken back her maiden name and Baker could have been her name from her first marriage but she pretended to Alfred not to have been married before. So I guess the answer is she could have had a maiden name of Baker, but there's no smoking gun proof at the moment.