The Miracle of Mindfulness is written by Zen master Thich Nhat Hanh. This is first book I have read about Zen or Mindfulness. Highly recommend this for mindfulness beginners. Very easy to digest the concepts he is talking about. You can easily complete reading it in 3 to 5 days. I also really liked the short story/anecdote format, really well written.
Even if you just implement one thing from the book if will have profound effect in your way of thinking, on your life. It makes you aware about your consciousness and things around you. If practice well, you can be calm in worst of the conditions.