Not much is known about her early life. However, she is in high-school as said by Ted to the Once-ler. Audrey is either 14 or 15 because in the daydream, she has like 15 candles on her birthday cake.
She told Ted that there was once real trees that create oxygen and are planted in dirt, but that they have been mostly ruined by industrialists and corparations. Wanting to gain her love, Ted speaks to the Once-ler, who is guilty of depleting the forest outside of Thneedville. She later assists Ted in restoring trees to Thneedville with the final seed. It was Audrey who told the town about how trees make oxygen for free, and that they neither "spray out sticky stuff" (a lie spread by Aloysius O'Hare) or pollute. She kissed Ted as he planted the seed.