You will learn a lot about grappling from Eddie's two "Mastering" books but the extra content in the book justify the price alone. Eddie's background, concepts on grappling, personal philosophy etc makes for good reading.
I am not much of a book guy for Jiu Jitsu, and will only buy it if there isn't a DVD option. Mastering the Rubber Guard should be committed to memory. Not only is it a base for every technique and thread on here, but it gets you really familiar with the terminology.
I have to look at my library to see what else - but a lot of it is a little more advanced.