
In 1996, Boynton began writing and producing songs.which she has described as "renegade children's music" - with composer Michael Ford these songs have been released as albums ( Rhinoceros Tap, Philadelphia Chickens, and Dog Train) and also published as book and audio disc sets.

More than 20 million copies of her books have been sold. Three Boynton books are on the Publishers Weekly All-Time Bestselling Children's Books list. Four of her books have been New York Times best sellers: Chocolate: The Consuming Passion (1982) Yay, You! (2001) Consider Love (2002) and Philadelphia Chickens (2002), which reached the number one position on the list, and was on the list for nearly a year. Nearly all of Boynton's books have been published by either Workman Publishing or Simon & Schuster. Her books are most typically for very young children, offered in the laminated paperboard format known as board books. Since the 1977 release of Hippos Go Berserk!, Boynton has published many children's books, as well as several illustrated humor books for the general market. (To which she customarily responded, "Only marginally.") Boynton reports having been often asked if she was related to "the guy who does the cards". As the greeting cards were signed simply "Boynton," many consumers assumed the creator to be a man. The best known of these is a 1975 birthday card bearing images of four animals and the message "Hippo Birdie Two Ewes," a pun playing on the phrase "Happy Birthday to You." The card has sold over ten million copies to date.

According to RPG co-founder and president Mike Keiser, over 200 million copies of Boynton's distinctive humorous cards.featuring an assortment of unnamed cartoon animal characters, spare layout, and droll messages.sold between 19. Boynton's greeting card designs for Recycled Paper Greetings were at the forefront of the Alternative Cards commercial movement that began in the mid-1970s.
