Openly Available Sources Integrated Search (OASIS) is a search tool that aims to make the discovery of open content easier. OASIS currently searches open content from 75 different sources and contains 176,005 records.
The Mason OER Metafinder allows you to simultaneously search across the multiple OER repositories (e.g., MERLOT II, OAOpen.org, OER Commons, OpenStax CNX, etc.) as well as many open archival repositories (e.g. HathiTrust, Internet Archive, Project Gutenberg, etc.).
Open textbooks are free, online learning materials with Creative Commons licenses. Many of the collections will have links to the same books, but each will have a particular focus, and items you can't find in other collections.
While not OER, there are electronic and physical resources available to you through Blough-Weis Library. These are available to students at no extra cost, but are restricted to students and university staff so they do not allow for customization and re-use in the same way as OER. Before adopting material provided by Blough-Weis Library, contact a librarian to discuss licensing & access issues as some content does not allow for simultaneous usage.
Below are links to resources where you can search our physical and electronic holdings.