Goodnight Moon author Margaret Wise Brown’s unpublished lullabies have been published in a new book.

Brooklyn-born writer Margaret Wise Brown is best known for her children’s book Goodnight Moon, a classic that’s inspired many parodies, including the delightful Goodnight Dune. She was only 42 when she died in 1952, leaving behind what Publishers Weekly’s Sally Lodge describes as “a treasure trove of unpublished manuscripts,” including a collection of lullabies that’s being published by Sterling Children’s Books this month.

Lodge writes that the songs/poems that comprise the book were discovered by Amy Gary, co-founder of the Alabama-based publisher WaterMark, who visited the home of Brown’s sister, Roberta Rauch, on the advice of several librarian friends (moral of the story: listen to your friends, especially when they’re librarians). Visiting Rauch in 1990, Gary wasn’t expecting to come across something that she’d be able to publish. “I asked Roberta if any of her sister’s unpublished manuscripts existed,” she told PW, “even though I assumed that if they had, someone would have already found and published them. But Rauch informed her that there was a trunk (a literal treasure chest!) in her barn attic with a collection of manuscripts, including the unpublished songs.

Gary took on the task of developing them into a collection, with Rauch’s permission, which turned out to be a lengthy process, since Brown would often use phrases that had appeared in her published works. “Researching the rights to her lyrics took many years,” Gary explained. It wasn’t until 2011 that she was able to place the book with a publisher, choosing Sterling in part because of its 2007 edition of Puff the Magic Dragon.

The new book is packaged with a CD of the lullabies performed by Emily Gary and Tom Proutt. It features illustrations contributed by twelve artists, each one paired with a different song by art director Meredith Harte. Illustrator Carin Berger describes her experience working on the artwork for “When I Close My Eyes at Night”:

I adored Goodnight Moon when I was little. I not only loved the story, but was entranced with Clement Hurd’s illustrations of the room itself. The images perfectly mirrored the words and had such presence – an evocative combination of warmth, quiet, and mystery. It was a thrill and honor to be asked to contribute an illustration to Goodnight Songs. I wanted the art to harken back to the room in Goodnight Moon, but instead of peeking in, this time I wanted to imagine peering out. I wanted to show rooms in all of the other houses in which goodnight stories were being read.

Goodnight Songs is out this week from Sterling.