From A Tom Sawyer Companion by Mark D. Evans:

Becky Thatcher

Tom and Huck make plans to cure warts at the graveyard later that night, and Huck trades his tick for Tom’s tooth. Tom races to school, and as a punishment for being late, he is forced to sit with the "new girl," Becky Thatcher.

Presently the boy began to steal furtive glances at the girl. She observed it, "made a mouth" at him and gave him the back of her head for the space of a minute. When she cautiously faced around again, a peach lay before her. She thrust it away. Tom gently put it back. She thrust it away again, but with less animosity. Tom patiently returned it to its place. Then she let it remain. - Tom Sawyer, chapter 6

On October 9, 1908, Twain wrote to a twelve year old Denver girl whom he had met in Bermuda. He asked her if she liked romances and then proceeded to tell about "the very first sweetheart I ever had." He was referring to Annie Laurie Hawkins, or more familiarly, Laura Hawkins. (SCH)

She was 5 years old, and I the same. I had an apple, and I fell in love with her and gave her the core. I remember it perfectly well and exactly the place where it happened, and what kind of day it was. She figures in "Tom Sawyer" as "Becky Thatcher." Or maybe in "Huck Finn" - anyway it is in one of those books. - Letter to Margaret Blackmer October 9, 1908 (SCH)