The Agile Samurai by Jonathan Rasmusson
A simple, easy to read and highly informative introduction for team members transitioning to agile, it covers everything from changing requirements to relative estimating.
Succeeding with Agile by Mike Cohn
Comprehensive introduction to the process and challenges of transitioning to Scrum
Agile Retrospectives: Making good teams great by Esther Derby and Diana Larsen
The definitive book on getting the most out of your retrospectives – an easy read and indispensable guide for retrospective structures & activities.
Coaching Agile Teams by Lyssa Adkins
An excellent reference guide for Scrum Masters, Coaches & Project managers who have transitioned to Agile.
Collaboration Explained by Jean Tabaka
Another excellent resource book for understanding team collaboration and facilitating for a variety of different conditions.
Gamestorming by Dave Gray, Sunni Brown and James Macanufo
This is the book to read when you’re ready to extend your facilitation toolkit.