These resources will not only allow you to search for quality open educational resources, but they are also capable of storing your own open courses to share with other educators. These resources are all free to use with or without a registered account. Oasis, M.O.S.T. OER Ready-to-Adopt Courses, and Mason's OER Metafinder are the quickest and easiest ways to find resources for you course.
These resources provide access to open textbooks; however, they also provide access to many other learning materials.