So this is a topic that was mentioned on EngineerBlogs back in February, but in preparing for my first ever lecture, I've been very thankful for my rather extensive bookshelf. I was lucky that I could afford not to sell back textbooks as an undergrad, and my husband kept most of his, which means I've got a pretty good collection to draw from. Here are some of my favorite references:
Fundamentals of Materials Science and Engineering, W.D. Callister (also acceptable: Materials Science and Engineering: An Introduction) This is the standard textbook of introductory materials science classes for a reason. It is fantastic! The index is thorough, the chapters are descriptively titles, and above all, it has some of the best figures. Materials science can be a very, very visual field, and knowing wheter it "looks right" is a critical skill to learn.
Undergraduate Instrumental Analysis, Robinson, Skelly Frame and Frame. This was honestly not a useful book when I got it for class, because in that class, we were always told what characterization equipment we would be using. Now, though, it's a great reference for any characterization technique, covering the basic physics of how it works, common pitfalls, and basic descriptions of the equipment.
(online, because there's 22 freaking volumes of awesome) ASM Handbook Online (subscription required) While my university has a subscription to these handbooks, being a member of the ASM professional society will also get you access. While the focus is on metals, since it used to be the American Society of Metals, these are a great resources for finding teaching examples. If you're a mechanical engineer with a metals question, they are a great place to start your search.
I could probably keep going through my bookshelf, but we quickly get into rather more specialized texts. These are great when you have a very specific issue, but for more general questions, I turn to these first.