She began writing in earnest in the mid 50s, returning frequently to Alabama to nurse her ailing father. One Christmas in Manhattan, a songwriter friend and his wife gave her a unique gift—a year’s income, to support her writing. (The songwriter was Michael Brown, who made his reputation and probably his fortune producing industrial musicals for clients like DuPont and Woolworth.)
She used it to write the first draft of To Kill A Mockingbird. It won the Pulitzer Prize for Fiction in 1961, and remains among the top 10 best selling novels from then until now. It is one of the five most assigned novels in American schools, and American librarians recently voted it the best novel of the twentieth century.
Harper Lee transformed memories of her childhood: her father was the inspiration for Atticus Finch, Truman Capote became Dill, and that ghostly young man was the probable prototype for Boo Radley. (That story is not well known, by the way. I found it in an academic thesis online by the director of a University of Alabama production of the play, who visited Monroeville.)
To refresh your memory of the story: Atticus Finch is the widowed father of the tomboy Scout (Harper Lee’s self-portrait) and Jem (Scout’s older brother). Atticus is a lawyer appointed to defend Tom Robinson, a young black man falsely accused of raping a white woman. This event is based partly on a case of her father’s, and partly on the infamous Scottsboro Trials of young black men falsely convicted of raping a white woman, also in the 1930s, when Harper Lee was about the same age as her fictional stand-in, Jean-Louise, known as Scout.