Michael Pollan. I found his The Botany of Desire: A Plant's-Eye View of the World to be worth picking up just for the section on apples. His discussion on the potato was fascinating to me as well. This video, from a TED conference, touches on the main theme of the book.
I just finished In Defense of Food: An Eater's Manifesto. it was not as much the page turner for me as the first book, but it has greatly influenced my thinking about what I want to eat. The credo of "Eat food, not too much, mostly plants" made a lot of sense once I started to think about how much of what we eat is actually manufactured rather than produced or grown. Clearly, if I am really going to follow his advice, I will have to make some changes that I may not be prepared to make. "Food", as Pollan defines it, has less than five (5) things in it. This rules out much of what is found in the local mega mart such as bread, cereals, and almond milk (very unfortunate for me). Anything with high fructose corn syrup should be avoid as well. Of course, if I was following the tenets of Locovorism I would not be buying any of that anyway.
Currently, I am still working my through The Omnivore's Dilemma: A Natural History of Four Meals, so I am not prepared to comment on it just yet.