On Findagrave.com, by Bette Grimm Thatcher:

“First, I want to say that my grandmother NEVER had a middle name. She didn't like them and didn't give her kids any either. The reason she has a "M" on her tombstone is that her grand daughter, Faye Brown, believe that she did without asking anyone in the family. She ordered the tombstone and added it herself. I told her before she died that she made a mistake because my grandmother told me that she didn't like them. I grew-up with my grandmother.”