If you want to know more about Opal, here are some places to start.
Opal Whiteley's Home Page. Information about Opal events, books and collector's items, with writings on Opal by Steve Williamson.
Liloriole's Fairyland has published The Fairyland Around Us and other writings online.
The Bookmine, 702 E. Main Street, Cottage Grove. (541) 942-7414. Ongoing display of Opal information, including books, articles, and "Opal's Fairyland," a free self-guided tour written by Steve Williamson. Benjamin Hoff sometimes comes down for the "Opal Whiteley Weekends."
The Singing Creek Where the Willows Grow: The Mystical Nature Diary of Opal Whiteley, by Benjamin Hoff and Opal Whiteley. (Penguin Books, New York, 1994.) Reprint of the diary with Hoff's complete commentary and biography of Opal. Currently in print.
Opal: the Journal of an Understanding Heart, by Jane Boulton. (Crown Trade Paperbacks, New York, 1995.) Poetry adaptation of parts of the diary. Boulton also prepared Only Opal, a children's book version (Philomel Books, Putnam, New York 1994.) Both currently in print.
Fabulous Opal Whiteley, by Elbert Bede. (Binfords and Mort, Portland, 1954.) Compendium of Bede's decades of newspaper articles, reworked into book form, by the man usually credited with "discovering" Opal. Currently in print.
Opal Whiteley: The Unsolved Mystery, by E. S. Bradburne. (Putnam & Co., London, 1962.) A reprint of the diary, with a lengthy commentary from the British point of view. Out of print for many years, it is now available in a reprint.
Special collections at the University of Oregon Knight Library in Eugene, Cottage Grove Public Library, Oregon Historical Society in Portland, and the Oregon State Library in Salem have a fair amount of material concerning Opal. Some of it is quite fragile, and use is restricted.
The Massachusetts Historical Society also has a collection, focusing on Opal's time working with The Atlantic Monthly.