Here is an article from Atlas Obscura from 9/4/2020 titled, “There’s Something About Mount Shasta.” It talks about Telos, the lava tubes and all things supernatural about the area. There are also pictures of the mountain – some are historic.
The Most Haunted Places in California has everything from Alcatraz to Bodie, the ghost town. Not much listed in California but an informative article for ghost hunters. I haven’t heard about any ghost stories around this area, but I’m sure there are plenty.
Here is an article about the haunted places in Siskiyou county. Everything from JFK and Black Bart, to Big Foot and Lemurians. The most concise list I could find.
An entire website dedicated to ghostly encounters around Yreka, California. People are able to leave a description of their own encounters, and there are links to ghost books and other websites dedicated to spooky happenings in the area.