Letts' publicist, Arlene Johnson, says Letts died yesterday after a brief illness. Letts was 76.
Letts' novels include "Where the Heart Is," which was turned into a movie starring Natalie Portman, Ashley Judd, Stockard Channing and Joan Cusak. Letts also taught English and creative writing at Southeastern Oklahoma State University in Durant.
She is survived by three sons, Dana Letts, musician Shawn Letts and playwright and actor Tracy Letts. Tracy Letts won a Pulitzer Prize for his play "August: Osage County," which was also made into a movie starring Meryl Streep and Julia Roberts.