Question: Which film did Eileen Heckart star in three years before The Bad Seed?

Context paragraphs:
Vicki Caroline Cheatwood: Vicki Caroline Cheatwood is an American playwright and screenwriter, who has been produced Off-Off-Broadway and throughout the United States.  In 2002, her screenplay "Air" (Escopa Films) won the Special Jury Gold Award at Worldfest Film Festival, and in 2005, the dark comedy feature "10:10" was a finalist in the Austin Film Festival.  In 2009 her short film "Break" premiered in New York.  She has been a finalist for several national playwriting honors, including the Heideman Award ("The Risen Chris", Actors Theater of Louisville), The Julie Harris Playwright Award ("An Hour South"), and the Eileen Heckart Drama Award ("Manicures & Monuments").  Current front-burner projects include the feature film script "The Road Goes On Forever", based on the hit song by Robert Earl Keen (Caliber Media Company, Beverly Hills, CA).

No Way to Treat a Lady (film): No Way to Treat a Lady (1968) is a black comedy thriller directed by Jack Smight, with a screenplay by John Gay adapted from William Goldman's novel of the same name.  The film starred Rod Steiger, Lee Remick, George Segal and Eileen Heckart.  Segal was nominated for a BAFTA for his role as Detective Moe Brummel.

Burnt Offerings (film): Burnt Offerings is a 1976 American mystery horror film co-written and directed by Dan Curtis and starring Karen Black, Oliver Reed, Bette Davis, Lee H. Montgomery, Eileen Heckart and Burgess Meredith.  It is based on the 1973 novel of the same name by Robert Marasco.  The story concerns a family who moves into an old house that regenerates itself by means of feeding off the life force of any occupant that is injured or in pain.  Other family members are all killed off, with the survivor awaiting a new family.

Bus Stop (1956 film): Bus Stop is a 1956 American romantic comedy film directed by Joshua Logan for 20th Century Fox, starring Marilyn Monroe, Don Murray, Arthur O'Connell, Betty Field, Eileen Heckart, Robert Bray and Hope Lange.

Up the Down Staircase: Up the Down Staircase is a novel written by Bel Kaufman, published in 1964, which spent 64 weeks on "The New York Times" Best Seller list.  In 1967 it was released as a film starring Sandy Dennis, Patrick Bedford, and Eileen Heckart.

Relative Fear: Relative Fear (also known as The Child and Le silence d'Adam) is a 1994 Canadian, independent, psychological horror film that references the 1956 film "The Bad Seed".  An autistic child is seemingly born to kill, and so he does.

Mommy (1995 film): Mommy is a 1995 American low budget thriller starring Patty McCormack as a mother who is psychotically obsessed with her 12-year-old daughter Jessica Ann (Rachel Lemieux).  McCormack is best known for her role as Rhoda Penmark in the 1956 film "The Bad Seed".  It is an unofficial sequel to The Bad Seed.

The Bad Seed (1956 film): The Bad Seed is a 1956 American psychological horror-thriller film with elements of melodrama and film noir, directed by Mervyn LeRoy and starring Nancy Kelly, Patty McCormack, Henry Jones, and Eileen Heckart.

Eileen Heckart: Eileen Heckart (March 29, 1919 – December 31, 2001) was an American actress of film, stage, and television.  Primarily known as a character actress, her career spanned nearly 60 years.  She first became known for her role as schoolteacher Rosemary Sydney in the original 1953 cast of William Inge's play "Picnic" on Broadway.  She won an Academy Award for Best Supporting Actress for her performance as the overprotective mother of a blind adult son in "Butterflies Are Free" (1972), a role she originated on Broadway before playing it in the film.

The Tree (1969 film): The Tree is a 1969 American film that was written, produced, and directed, by Robert Guenette.  A psychological drama revolving around the kidnapping of a young child, the film stars Jordan Christopher, Eileen Heckart, Alan Landers, Gale Dixon, James Broderick, Kathy Ryan, Ruth Ford, and George Rose.

Supporting paragraphs: The Bad Seed (1956 film) Eileen Heckart
Answer: "Picnic"