My friend gave me Encounters with the Archdruid for my birthday four or five years ago. It is a good read, deals with environmentalism.
Since I enjoyed two of his books, I picked up a few more at one of those super discount bookstores last year for $3 or $4 each. Between the baby and work, I only had the time to start one so far - Coming Into the Country. I'm about halfway through and enjoying it so far. It's about Alaska entering the union, great view of Alaska during it's early statehood.
I also bought The Control of Nature and Irons in the Fire, but they are buried at the bottom of a pile of about twenty books, so it's going to be a while.