Despite what people think, librarians are very good at throwing books away. We have to, we need all the space for new books and if a book doesn't get checked out enough, into the trash it goes, unless it's a classic (but then a new edition may help) or the information is not available elsewhere.
But I still like to see other uses for old books than just throwing them out. Growing mushrooms on them for example. You can make your own mushroom spawn or you just buy it online.. Soak the book - a thick paperback with three hundred pages or more - in warm water for a couple of hours and then spread the mushroom spawn between the pages. I used The Mists of Avalon because it's nice and thick and because it was one of the most boring books I had ever read. I put fifty pages or so between every layer of spawn, with a thinner book you may want to use less pages.
I left the book open like that, a thin book can be closed.
Put the book somewhere out of direct sunlight, but not in the dark, and at room temperature. I had it on top of a kitchen cabinet across the room from the window. Mist the book every day and wait.
After five days or so the first strands started to appear and after ten the whole book was covered in it. There was some mildew, but I just removed the top pages to get rid of that. The the first actual mushrooms started to grow (I know, those are just the mushrooms fruiting bodies, but you know what I mean).
After twenty days:
Here's a online shop in the UK that sells mushroom book recycler kits, but you really just need an old book and mushroom spawn. I bought oyster mushroom spawn because they seem to grow well on books and one litre of spawn was more than enough for this book, I have enough left for a second one (stored in the fridge). I want to try shitake mushrooms next because they can be dried much better than oyster mushrooms.