It sounds like you’re asking about this topic because of an assignment and are looking for reliable sources that you can cite in your writing. While reddit is a creative place to go for suggestions, in an academic context, you might get more reliable results by searching a library catalog.

If you are interested in a very broad topic like “Native American Religion,” one effective strategy is to type this set of keywords into the catalog search bar of your library, and then browse results until you find a book that sounds relevant. Look for the subject keywords that are hyperlinked in the record (often towards the bottom of the page), and click those to see a list of titles that have also been tagged with those keywords. In this case, the subject string will probably start “Indians of North America.” Subject searching can be a bit fiddly, but your librarian (university, school, or public) generally loves to be asked about this sort of thing. They can help you (possibly virtually, depending on your local situation at the moment) develop additional search strategies as your research develops.

Also, you should know that the language used in library catalogs to describe indigenous peoples has a complicated history of bias and discrimination. You might look into the Brian Deer Classification System for more information on this subject, or view the recent documentary “Change the Subject” to learn more about the intersection of current politics and library classification.