Patty Petersen was written into the cast of the Donna Reed Show as Trisha, an adopted child shortly before Shelley Fabares left the series. She stayed with the show until it ended in 1966. She is the real-life sister of Paul Petersen, who portrayed Jeff Stone on the show.
After several commercials and industrial films, she retired to raise a family of her own. Now known as Patti Petersen Mirkovich, she is the founder of an Internet company for novice authors, and is a teacher of computer studies for elementary, high school and adults. She serves on the Board of Directors for the Donna Reed Foundation for the Performing Arts. She has two children, Tim and Melissa.