A floppy-eared protagonist who would be called Bunny Rabbit in the straight-talking world morphed into Runny Babbit in the inimitable imagination of Shel Silverstein, and first appeared in Runny Babbit: A Billy Sook. This collection of spoonerisms, illustrated with the poet’s trademark black-and-white drawings, was published by HarperCollins Children’s Books in March 2005, five years after Silverstein’s death. The amiable rabbit will make a second appearance on September 19, when the publisher issues a companion volume, Runny Babbit Returns, whose cover is revealed here.

Silverstein, who was also a gifted cartoonist, playwright, performer, songwriter, and recording artist, has charmed generations of young readers with his children’s poetry collections, which have sold more than 39 million copies in the U.S. alone and have been translated into 46 languages. His tongue-twisting, letter-swapping wordplay in Runny Babbit obviously tickled kids’ funny bones: the book has sold more than 770,000 copies.

Senior executive editor Antonia Markiet, who acquired U.S. and Canadian rights to Runny Babbit Returns, collaborated with members of the late author’s family to select the poems included in the volume. Family members culled the Silverstein archives and shared with Markiet and her team poems and drawings that he had included in preliminary versions of his first spoonerisms collection, but that hadn’t made the final cut. “The family would come to our offices every month, and we’d work for a day or two,” Markiet recalled. “We’d read through the poems together, and tried to choose the most appropriate and cleverest material that was in the spirit of the original book.”

Yet even using Runny Babbit as a model, making the final selection was a painstaking task—one that Markiet estimated took about a year and a half. According to the editor, Silverstein’s family offered valuable, informed input as the book took shape. The poet had habitually asked for their opinions of his works in progress, and some of their comments were visible on drafts of his Runny Babbit poems.

“We really trusted his family’s decisions, since they had been so involved in Shel’s work,” Markiet explained. “And I had worked with him in the late 1970s, when I was probably an associate editor at Harper, so I was familiar with how he liked to work. Shel was so good about asking me what I thought about this or that, but I’m afraid I wasn’t always brave enough to say very much!”

To make the final selection of 41 poems, Markiet and her colleagues laid the spoonerisms and art out on the floor, running down a couple of corridors. “We walked back and forth, moved things around, and redirected the order of the poems,” said the editor. “It was really hard, but several things helped us make choices. We didn’t want too many duplicate themes—monsters, food, and the like—and some poems didn’t have illustrations accompanying them, so they were eliminated.”

Markiet was reassured by the knowledge that the poems and art were “complete and ready for publication,” and up to Silverstein’s exacting standards. “Shel was such a hard worker, and revised and revised until he felt something was right—and finished,” she said. “I have no clue how great illustrators know when a work is done. Something niggles, and they come back to it until they reach the spot where it finally works for them. Shel would look at an illustration for a bit, and announce that we had to move this or that an eighth of an inch to the right. And we did, and the balance was better. Shel just knew what worked and when it worked—and he was always right.”

Given Runny Babbit’s enthusiastic reception and robust sales, the editor was grateful that Silverstein’s fans “made the effort to try something new” from the author. “Looking through the poems, sometimes we’d read them aloud straight, without the spoonerisms, and found that they work fabulously well even without the letter switches,” she said. “But the spoonerisms give the verse extra playfulness. They are so typically Shel—so much his sense of fun and humor. We are so pleased to have this opportunity to share another Runny Babbit book with readers.”

Runny Babbit Returns by Shel Silverstein. HarperCollins, $19.99 Sept. ISBN 978-0-06-247939-6