Bhikkhu Thanissaro is doing an amazing public service that deserves more recognition and gratitude. On his site, dhammatalks.org, he has made a significant portion of the Sutta Pitaka, the ancient Buddhist scriptures, available—free of charge—in a series of compilations. Included with these compilations are an assortment of helpful essays, treatises, and study guides.
His renderings of the verses from the Samyutta Nikaya and Sutta Nipata are particularly refreshing, and provide clarity to the commercially available translations that are sometimes more cryptic due to their more literal translation.
I recommend starting with The Buddha’s Teachings: An Introduction, which provides a brief introduction to Buddhist practice, and then reading The Wings to Awakening to get a feel for the teachings in more detail. If you’re just interested in mindfulness and meditation, try the treatise With Each & Every Breath: A Guide to Meditation.
dhammatalks.org also has a podcast that you can subscribe to via rss feed or YouTube.
The Buddha summarized his teachings very succinctly in the 22nd sutta of the Majjhima Nikaya: “One thing and one thing only do I teach, suffering and how to end suffering.” 
This is expanded upon by the Four Noble Truths, which—in essence—state: 1) dissatisfaction exists, 2) it exists because we cling, 3) therefore we should stop clinging, 4) following the Eightfold Path can mitigate our clinging and dissatisfaction. .
And the Eightfold Path , in short, is:
- Right View: accept reality
- Right Intention: strive toward frugality and goodwill
- Right Speech: avoid deceptive, harmful, and idle speech
- Right Action: avoid killing, stealing, etc
- Right Livelihood: pursue careers that don’t harm others
- Right Effort: act with diligence
- Right Mindfulness: value the moment
- Right Concentration: meditate
And that’s pretty much it.
 The Snake Simile (MN 22)
 Setting the Wheel of Dhamma in Motion (SN 56.11)
 Eightfold Path for the Householder
The Buddhist “bible” is called the Tipitaka. It’s a massive collection of texts that were first compiled by the Fourth Buddhist Council in 29 BCE. It’s divided into 5 nikayas (volumes). One of my favorite nikayas is the Samutta Nikaya, the 3rd volume, pictured here. As you can likely tell from the thickness of this book, the Buddha had a lot more to say than the handful of inspirational quotes floating around on social media.