There are many excellent books about Buddhism. Here is a selection that provides an introductory foundation to Buddhism. Other introductory books on Buddhism can be found here.
An Open Heart: Practicing Compassion in Everyday – HH the Dalai Lama
Buddha – Karen Armstrong
Buddha: His Life and His Teachings – Walter Henry Nelson
Cave in the Snow – Vicki McKenzie
The Clouds Should Know Me By Now: Buddhist Poet Monks of China – Pine & O’Connor
Cutting Through Spiritual Materialism – Chogyam Trungpa
Daily Wisdom: 365 Buddhist Inspirations – Josh Bartok
Dhammapada: The Sayings of the Buddha – Thomas Cleary
Enlightened Journey, Buddhist Practice As Daily Life– Tulku Thondup
A Flash of Lightning in the Dark of Night: A Guide to the Bodhisattva’s Way of Life – Dalai Lama
Gates to Buddhist Practice– Chagdud Tulku
Guide to the Bodhisattva’s Way of Life – Santideva
Healing Power of the Mind – Tulku Thondup
Hidden Teachings of Tibet: An Explanation of the Terma Tradition of Tibetan Buddhism – Tulku Thondup
Introduction to Tantra – Lama Yeshe
Open Heart, Clear Mind – Thubten Chodron
Opening of the Lotus: Developing Clarity and Kindness– Sherab Gyaltsen Amipa
Relating to a Spiritual Teacher – Alexander Berzin
Start Where You Are – Pema Chodron
Taking the Bodhisattva Vow – Bokar Rinpoche
Teachings of the Compassionate Buddha – E.A. Burtt
Tibetan Buddhism from the Ground Up – Allan Wallace
Transforming Problems Into Happiness – Lama Zopa
When Things Fall Apart: heart Advice for Difficult Times – Pema Chodron
Words of My Perfect Teacher– Paltrul Rinpoche
Zen Mind, Beginner’s Mind – Shunryu Suzuki