Researchers looking to locate either publisher, or funding agency policies have two excellent resources to turn to, SHERPA/RoMEO, and SHERPA/JULIET.
UNB Libraries' guide to the Tri-Agency Open Access Policy on Publications.
SHERPA/RoMEO is a database hosted by the University of Nottingham that seeks to contain up-to-date open access policies for as many academic journals and publishers as possible. Users can search the database for a specific journal to find out what their rights are in terms of sharing their research.
SHERPA/JULIET is another University of Nottingham database that contains up-to-date open access mandates and requirements for as many funding agencies as possible. Users can search the database for a specific funding agency in order to determine their open access requirements.
Adapted from the CAUL/CBUA Scholarly Communications Committee Digital Scholarship Toolbox Gitbook.