The American Institute of Mathematics (AIM) maintains a list of open source and open access mathematics textbooks that have met the AIM Editorial Board’s evaluation criteria and are suitable for use in traditional university courses.
Multimedia Educational Resource for Learning and Online Teaching (MERLOT) is a curated resource of free and online textbooks for use in teaching and learning. Use the filters to limit to Open (Access) Textbook and College Lower Division.
My Open Math allows students to study math concepts on their own. For faculty, it offers options for including open educational resources and textbooks within your courses. My Open Math has recently worked with Virginia community colleges to create a statistics textbook with Open Stax.
Project MUSE offers open access (OA) books and journals from several distinguished university presses and scholarly societies. These books and journals are freely available to libraries and users around the world.
A collection of high quality, free-to-use courses that you can download and use for teaching. All content is stored in Google docs making it easy to access, browse and download. From the Washington State Board for Community and Technical Colleges.
A consortium of over 250 community colleges that support Open Educational Resources. The website includes both resources and textbooks for community colleges as well as periodic webinars aimed at community colleges.