My take, having never seen or heard of this book before in my life and only having this picture of the cover to go on:
The book is called Ellison Wonderland, a takeoff of the title Alice In Wonderland, a story in which mushrooms play a part. In the picture there are mushrooms behind Harlan. The foremost one has pieces cut out of it. It looks like Harlan is holding the pieces that were cut out. They are mushroom pieces.
Ah! That explains everything!
