I had two. Corduroy by Don Freeman and Bedtime For Frances by Russell Hoban.
I got them both as books on tape when I was about 6. I could already read by then, but I would put them in a little walkman and listen to them when I went to sleep.
I had a little brown bear. I dressed him up in green overalls that I had made and named him Corduroy. I would pretend I was Lisa, and even arranged my room to look like hers in the book.
When I couldn't sleep, I'd listen to Bedtime For Frances, and when the book was finished, I'd try my own ABC song, like she had in her attempt to fall asleep.
To this day I still have those books, both of them, WITH THEIR TAPES. Yep. I'm a dork, but I got to share them with my kids. :)