Great news. I just found out that an audio version of Can Hens Give Milk? is in the works.
Also - artists keep asking me how to get into the book illustration business. I'm not an artist, but I do know how this works and how it doesn't work.
Do not ask a writer to collaborate on a book unless you are both well known in the field. Publishers like to be in control and to match a writer with an illustrator.
Do go to the local library, or bookstore, and find this year's edition of Children's Writer's and Illustrator's Market.* See what each publisher wants, and how to submit samples of your work - and then go for it.
Do ask an illustrator for advice and tips.
*This is where the apostrophes are in some of the Google sites. It's a bit ambiguous, isn't it? I've settled on the above.