When 29-year-old Stephanie Appell, who works at Parnassus Books in Nashville, Tenn., was diagnosed with breast cancer last April, the staff wanted to do something to help her focus on healing. The store's co-owner, novelist Ann Patchett, suggested asking authors appearing at the store to decorate ceramic piggy banks that could then be sold to raise money for Appell’s medical expenses.

“We thought we would get 20 authors,” said the store's social media director Mary Laura Philpott, who is also the author of Penguins with People Problems. “We had no idea it would grow into a movement.”

But once the word got out more than 100 authors and illustrators volunteered, including John Green, Jeff Kinney, Sandra Boynton, Paula Hawkins, and Lane Smith, the project grew.

Instead of just selling a few piggy banks at the store for Appell, who manages books for young readers, Parnassus set up an online auction with part of the proceeds also going to Binc, the Book Industry Charitable Foundation.

“Whether you’re one of ours or you’re a bookseller somewhere else, we think it’s our place to help,” said Patchett, who is serving with James Patterson as an ambassador to Binc this year.

The auction will take place over a number of days at Bidding Owl; it starts at 6:30 p.m. CT on September 25 and ends at 8 p.m. CT on September 30.

The piggies will also be on display at the store on the evening of September 25; a $10 donation is requested at the door.