Below are OER collections containing a variety of Math related course materials (e.g., readings, quizzes, simulations, assignments, and more). Since Math encompasses a variety of subject areas, you can search the following OER collections using keywords related to your specific courses.

Search OER Commons using keywords related to your specific courses.
Link: http://www.oercommons.org/

Browse American Institute of Mathematics for textbooks related to your math courses.
Link: https://aimath.org/textbooks/approved-textbooks/

Search MERLOT using keywords related to your specific courses.
Link: http://www.merlot.org/merlot/advSearchMaterials.htm
SEARCH TIP: OER Commons and Merlot allow you to further limit results by sub-disciplines and material type.