Play It as It Lays is a novel written by Joan Didion in 1970. The novel focuses on the life of Maria Wyeth, a woman with a turbulent life lacking much purpose or direction. The reader is introduced to Maria through her internal monologue. From her, we learn she is held in a psychiatric hospital located in Los Angeles after a mental breakdown.
Terrible things happen to Maria throughout the story. She undergoes the death of her mother in a car accident, the death of her father, and suffering through blackmail from her abusive boyfriend Ivan Costello. Maria also has an abortion.
In her lost state, Maria begins to compulsively and aimlessly drive along the California highways. In doing so, she finds some sense of calm. If she is not driving she begins to feel the weight of her past and her lack of future direction.
Maria eats hard-boiled eggs while driving since they are easy to crack and eat without losing focus. At one point in the story Maria is driving in her car eating eggs while talking to her agent and she asks him if he is, "playing with a Fabergé Easter Egg."
These are the only references to eggs in the story. Rather than stopping to eat a fulfilling meal, Maria chooses to eat an egg while driving so she does not have to think.
Eggs typically represent fertility and this is likely the case in Play It as It Lays, as Maria had an abortion. The eggs are just another reminder of the misfortune that has followed Maria throughout her life, and represent her inability to process her experiences in a healthy manner.