Peggy Sue Gerron Rackham, who became part of Buddy Holly’s circle of friends as a teenager and long reveled in having her name used as the title of one of his biggest hits, died on Monday in Lubbock, Tex. She was 78.

Her son-in-law, Tom Stathos, confirmed the death but said he did not know the cause.

As Ms. Rackham told the story, she was a sophomore at Lubbock High School in 1956 when she first encountered Mr. Holly, who had graduated a year earlier. She was walking to the school’s band room — she played alto saxophone — and he was rushing to the auditorium to attend an assembly.

He crashed into her, sending her to the floor, her books scattering and her poodle skirt rising over her knees.

“I’m terribly sorry, but I don’t have time to pick you up,” he said, as she recalled the moment in her autobiography, “Whatever Happened to Peggy Sue?” (2008). “But you sure are pretty.”