Michael Moore is a delight to read. He offers much information on his website and in his books. Humor is injected freely into his text, but his viewpoint on many herbs is that of someone who really does use them and knows what he's talking about. It's clear that he's confident in his approach, knowledgable and, best of all, willing to share.
He tells four methods of collecting, followed by an intense listing of herbs and their actions. Each herb lists a great general reference guide - one of the more honest ones out there, making it a true favorite. On some of the herbs I would have liked the information to be a bit longer, but overall its an excellent job and a guide I'll keep returning to.