Go to a library big enough to own the 2 volumes of Margaret Read MacDonald's Storytellers Sourcebook. They take a bit of work understanding how they are arranged & any abbreviations used, but can help you find stories half-remembered, or on a topic, or from a specific ethnic group or land. They're much more informative than the many volumes of the older Index to Fairy Tales, which also can help you find stories.
Fellow Professional Storyteller, Jackie Baldwin's site, http://story-lovers.com has a section called SOS: Searching Out Stories, a free archive of stories, sources, & advice drawn from the email list, Storytell.
National Storytelling Network is a great resource, too. If you were a member you could search their member directory for OR members. As it is, you might ask Yvonne Young, who's here on P.S. & is the OR State Liaison for NSN. She's in Eugene, OR, but will know her state resources.