Since you enjoyed Now We Are Six by A.A. Milne, I am including among the list of funny books, some humorous poetry as well. I hope you find some books that you will enjoy.
Hand, Hand, Fingers, Thumb by Al Perkins. Rhyming text describes what
can be done on a drum with hand, fingers, and thumb.
Cat Is Back At Bat by John Stadler. Fourteen rhymed verses describe
funny animals, for example, "A big pig tries a wig" and "A snake tries
to bake a cake."