Raised in logging camps in rural Oregon, Whiteley was considered by some a child prodigy, and expressed intense interest in both writing and science in her youth.

As an adolescent, she began tutoring and holding lectures on natural history and geology in her community, earning a reputation as an amateur naturalist, as well as becoming a noted speaker for the Young People's Society of Christian Endeavour.

Throughout her life, Whiteley claimed to have been the biological daughter of French naturalist Henri, Prince of Orléans, who died during an expedition in India in 1901, after which she was allegedly sent to Oregon and adopted.

The details surrounding her family history have been the subject of wide speculation, with several biographers attributing the claims to delusions stemming from mental illness.

[7] In 1903, after having spent almost a year in Wendling, Oregon, the Whiteley family moved to Walden, near the town of Cottage Grove, where Opal was raised largely in poverty.

Beginning at age six, she began writing a personal diary in which she observed the animals and natural world around her, sometimes using crayons, and utilizing her own phonetic form of spelling.

[12] At age eight, Whiteley joined the Young People's Society of Christian Endeavour, a fundamentalist group that encouraged "social growth and spiritual awareness" in rural communities.

[15] She concurrently became a leader of the local chapter of the Junior Christian Endeavor and gave talks in Portland; one attendee there recounted that she "spoke about God being everywhere, and how every little creature, plant, and tree in the woods bore testimony to His presence.

"[16] By age seventeen, Whiteley had been elected as the state superintendent of the Young People's Society of Christian Endeavor,[17] and her lectures on nature led to Cottage Grove Sentinel editor Elbert Bede writing a series of articles about her in 1915.

[22] She spent the summer of 1917 touring the state and giving nature lectures in an effort to earn money for her tuition, and resumed her studies in the fall of that year.

[24] In the spring of 1918, shortly after making her museum announcement to the public, Whiteley promptly left Oregon, traveling to Los Angeles with the intention of earning money through lectures to finance its plans.

[25] Publication efforts for The Fairyland Around Us began in December 1918, but its initial planned release never reached fruition as Whiteley ran out of funding to support it, largely due to her frequent requests for changes during the publishing process.

[26] Describing the book's manuscript, biographer Benjamin Hoff notes: "Like her other writings, it balanced seriousness with humor, scientific scrutiny with mysticism, and information with emotion.

"[25] Several months later, after regaining her health, Whiteley continued to pursue the project, eventually accruing enough funds to self-publish The Fairyland Around Us in a run of approximately 200–300 copies, featuring hand-pasted drawings and postcards in place of the plate illustrations that had been destroyed.

[26] Copies of The Fairyland Around Us were distributed on a subscription basis, and earned Whiteley praise from Theodore Roosevelt, William Howard Taft, and Kate Douglas Wiggin, who sent her letters of appreciation.

[26] I have read with interest a number of comments on The Story of Opal ... which not merely cry out that this remarkable testament of a child's heart must be tinctured with fraud but which deplore its 'sentimentalism' and even point to it as one more instance of the amazing American appetite for mush ...

[29] By some accounts, Sedgwick initially declined to publish the book, but, after interviewing Whiteley and finding her recounting of her life story intriguing, inquired if she had documented it in a diary.

[33] Based on its success as a serial, the Atlantic Monthly published the full work in book form as The Story of Opal: The Journey of an Understanding Heart.

[45] Furthermore, Hoff indicated that he had examined some of the few remaining diary pages and that chemical tests suggested that the crayons and paper had been manufactured prior to World War I.

[46] This claim was initially made in Opal Whiteley, The Unsolved Mystery by Elizabeth Lawrence, in which she noted that she had had the diary pages submitted for scientific scrutiny.

Historian Jennifer Chambers writes in Remarkable Oregon Women: Revolutionaries & Visionaries (2015) that "opinions differ widely" on the diary's origins, and that "whole books and dissertations have been written positing theories going both ways.

"[7] Hoff cites Whiteley's alternate account of her parentage as evidence of latent mental illness, and the fantasies rooted in her childhood fascination with India, where Henri, Prince of Orléans died during a 1901 expedition.

[49] Hoff asserts that Whiteley's mental illness was responsible for the ruinous circumstances that recurred throughout her life: When little Opal said the animals and flowers talked to her, people thought that she was lying.