Euporia is a platform aimed to foster the searchability and discoverability of Open Access philosophical resources and scholarly contributions on topics related to the philosophy of Open Science, digital culture and research ethics.
According to their website, "Get 1,500 free online courses from the world's leading universities -- Stanford, Yale, MIT, Harvard, Berkeley, Oxford and more. You can download these audio & video courses (often from iTunes, YouTube, or university web sites) straight to your computer or mp3 player. Over 45,000 hours of free audio & video lectures, await you now."
According to their website, "The B.C. Open Textbook Collection is home to a growing selection of open textbooks for a variety of subjects and specialties. Discover open textbooks that have been reviewed by faculty, meet our accessibility requirements, and/or include ancillary materials (quizzes, test banks, slides, videos, etc.)."
Probably the most-known and widely-used OER Textbook provider from Rice University, OpenStax has published multiple editions of open textbooks for high-school and first-and-second year college students.
According to their website, "Project Gutenberg is a library of over 60,000 free eBooks. Choose among free epub and Kindle eBooks, download them or read them online. You will find the world's great literature here, with focus on older works for which U.S. copyright has expired."