The Shrinking of Treehorn is about a boy who shrinks, and whose parents are too busy to pay attention. One of the illustrator's stepmothers was the woman who plays the guitar and sings the Marseilleise in Casablanca.
The Dud Avocado is (apparently) a racy taste of fifties Paris. It was written by an American heiress slash actress who knew Hemingway and Olivier, and married Kenneth Tynan. It got good reviews, and there was also this letter:
Dear Mrs Tynan, I don't make the habit of writing to married women, especially if the husband is a dramatic critic, but I had to tell someone (and it might as well be you since you're the author) how much I enjoyed The Dud Avocado. It made me laugh, scream and guffaw (which incidentally is a great name for a law firm). If this was actually your life, I don't know how on earth you got through it. Sincerely, Groucho Marx.