As a veritable card-carrying #bibliophile something I wanted to mention is that they could be worth quite a bit (or, conversely, very little at all); e.g., if you've got any of the circa 1960s Golden Book of X (X=chemistry, atomic power, etc), those can be worth thousands; if older reprints of certain Lewis Carroll books, it can be a coin toss, so would advise doing some research before auctioning them off.