Here are a few books and resources I often recommend:
Mindfulness
Mindfulness in Plain English by
Bhante Gunaratana
Mindfulness: A Practical Guide to Awakening by
Joseph Goldstein
Mindfulness and Insight: The Mahasi Method by
Mahasi Sayadaw
Metta
Loving-Kindness in Plain English: The Practice of Metta by
Bhante Gunaratana
Lovingkindness: The Revolutionary Art of Happiness by
Sharon Salzberg
Jhana
Focused and Fearless: A Meditator's Guide to States of Deep Joy, Calm, and Clarity by
Shaila Catherine
Dharma
The Noble Eightfold Path: Way to the End of Suffering by
Bhikkhu Bodhi
Being Nobody, Going Nowhere by
Ayya Khema
Zen Mind, Beginner's Mind by
Suzuki Roshi
Early Buddhism
In the Buddha's Words: An Anthology of Discourses form the Pali Canon by
Bhikkhu Bodhi, ed.
A Meditator's Life of the Buddha: Based on the Early Discourses by
Bhikkhu Analayo
Access to Insight is a great online resources for suttas and related articles.