MLA International Bibliography is published by the Modern Language Association, and it covers folklore and other topics related to language and literature.
Humanities Index also covers folklore, and it would be another good index to use for this topic.
Knowing which periodical index to use is the first step to finding good articles.
Then you need to know how to find articles on your specific topic within the index.
As you look at different periodical indexes, you will soon see that they have different ways of organizing the information. Most of the indexes use some type of controlled vocabulary (or subject headings) to identify articles on specific topics, and there might be a thesaurus to help you identify the controlled vocabulary.
It will take time to become familiar with the indexes you use most, but it will be a worthwhile investment. Time spent becoming familiar with the layout and features of a few key indexes will be time saved when you are working on a research project. Of course, you can always ask for help from a reference librarian.