Rimel was born to Pearl Guy Rimel and Florance F. (née Wilsey) Rimel on February 21, 1915, in Asotin, Washington.His father was a painter, while his mother worked as a secretary. In 1934, he graduated from Asotin High School.

H. P. Lovecraft began corresponding with Rimel after becoming aware of him in 1933. The resulting correspondence continued until Lovecraft's death in 1937. He introduced Rimel to F. Lee Baldwin, another author and resident of Asotin, Washington. Lovecraft tutored Rimel in the writing of weird fiction by giving him advice and weird texts from his personal library. He sent Lovecraft some early manuscripts, including a now-lost work titled "The Spell of the Blue Stone" in February 1934. Lovecraft regarded this story as being "very remarkable for a beginner's work". Next, he sent "The Tree on the Hill", which Lovecraft edited. This story was later published in the 1940 issue of the fanzine Polaris.

 In the summer of that year, Rimel sent a poetic manuscript titled "The Dreams of Yid". Lovecraft altered the title to "The Dreams of Yith", as Rimel had not been aware that the term "yid" is an offensive term for a Jewish person. Clark Ashton Smith also contributed to the revision.The sonnets were published in two issues of the Fantasy Fan.Lovecraft, who was professionally revising stories for clients, did not charge Rimel for his revisions. Instead, he viewed Rimel as needing help in his formative period as a writer.