Starting in 2000, the International Edible Book Festival has been happening around the globe and it is typically held on April 1st. The first year, there were festivals held at various locations in France, Australia, and throughout the USA. Since then, it has spread widely and has included participants in as many as 15 countries.
Some great entries from previous years that I've seen around the web:
My First Book of Shapes by Katherine Ng
Rosenkrantz and Guildenstern Are Bread by Aimee Meyer
Tail of Peter Rabbit by Judy Baily
Passover Haggadah by Gene Epstein
Pages of Peas by H. Mc Pherson
I have never attended a festival for this event; but, this year Tulibri invited others to submit photos for a virtual gathering. I almost missed it - which means I gave myself only a single afternoon to think of something and execute it! Two very chintzy concepts were realized. So for lunch, my little boy and I created Dr Toastus with a chunky exposed-spine chain stitch binding.
Later, I documented Life of Pie.