There is a lot of folklore and legends surrounding volcanoes. Why wouldn't there be? Huge, firey mountains start spewing forth, seemingly on a whim...
Share some of the stories with your students - they're usually quite short. I haven't found a good collection of volcano folklore in one place, but you can google 'volcano folklore' or the specific volcano you're interested in, such as 'Mt. St. Helens folklore' or 'Mauna Loa folklore'.
Of course, make sure you read through the stories before sharing them with your students, to make sure they're appropriate for your group!
After sharing a few stories, have your students try their hand at writing their own folklore. Perhaps you'll want to provide them with a picture (or multiple pictures) of a volcano to inspire their stories, or maybe you'll just let them have at it with their own imaginations.
You may also want to share the story, Hill of Fire with your students. It's based on the true story of the formation of a Mexican volcano in the middle of a corn field.