My introduction was "Mindfulness in Plain English" by Henepola Gunaratana. Gets you practicing right away while subtly introducing Buddhist ideas.
I've also heard "Being Nobody Going Nowhere" by Ayya Khema is a good introduction. I read it a few years in, but it's still an excellent book that covers all the basics.
"The Heart of the Buddha's Teaching" by Thich Nhat Hanh is great. It's a bit dense. I'd just read that a chapter at a time.
Namu Amida Butsu
"When people of the Pure Land school chant Namu amida butsu, they are doing zazen with their mouths, and when we do zazen, we are performing Namu amida butsu with our whole body." - Kosho Uchiyama (Opening the Hand of Thought)