I had to share this. I explained in this post why I named Matilda Jane that, but I think this might explain where the name's use as a pet name originates: 'Bessie's Song to her Doll,' by Lewis Carroll. It certainly sounds very familiar but I have no memory of reading it. I hated Alice in Wonderland as a child, and only read all of it a few years ago, but my mother knows most of the poetry by heart along with lots of Carroll's other poetry and I remember her singing them to me. Incidentally I have a beautiful 1887 edition of Alice.