Mrs. Miller was Kitch before Kitch was Kool.
She was discovered in the early '60s by LA DJ Gary Owens, better known as the announcer on Laugh-In. However, her star didn't begin to rise until she was signed to Capitol Records in 1965. According to the WikiWackyWoo:
Singing in an untrained, Mermanesque, vibrato-laden style, according to Irving Wallace, David Wallechinsky and Amy Wallace in The Book of Lists 2, Miller's voice was compared to the sound of "roaches scurrying across a trash can lid." 
While growing up in the '60s, I was fascinated by Mrs. Miller. I couldn't wait for her many appearances on the various talk shows of the day. I thought, "If she can make it in Show Biz, then so can I," which may have been my impetus for starting Cobwebs and Strange, a band I formed with my childhood friends.
According to Searching For Mrs. Miller:
From Claremont [where she lived] to Capitol is two hours in average traffic. There is a piece of story missing here, being that an organist/pianist on these sessions, Fred Bock, by all accounts a smart man with a sharp sense of humor, knew he'd found something unique. Fortunately, he knew somebody of consequence in the music business.
Lois Bock recalls: "Mrs. Miller would come to the L.A. studios and make recordings to send as gifts to orphanages those old, old songs like ` Alice Blue Gown' in what she called her `operatic style', and, on one of these sessions, Fred talked her into doing `Downtown', which he took to Lex, who was an employee of Capitol at the time, and he heard something there." She was signed to the venerated label, and work began on her debut, Mrs. Miller's Greatest Hits.
Barry Hansen, a/k/a Dr. Demento raised an interesting point. "It took some imagination on Lex De Azevedo's part to make an album of her doing all rock 'n' roll songs. It certainly was a departure from what she had recorded before." Conventional legend has it that Mrs. Miller had no idea that she was a novelty act, but Lois Bock is quite clear about what Mrs. Miller was told. "Fred and I were honest with her. We told her it would be funny. And the audience loved it. The more they laughed, the more she would, you know, work it. I don't know if she knew more than she let on, because she was always quite a character. But she loved audiences."
As Lois Bock said, "She had a good run for eighteen months, which was seventeen-and-a-half more than anyone had a right to expect." Mrs. Miller continued to perform sporadically, playing more benefits than just about any performer I can name, including one to raise funds to build a hospital in her hometown Jetmore, KS. When the hospital was built, she personally furnished the nurse''s lounge. She also devoted much time to raising her niece, Audrey.However, we still have her music to keep us warm on those cold nights:
[...] She retired officially in 1973, resigning from the Screen Actors' Guild in honorable standing, and eventually settled into a condo at 9535 Reseda Blvd in Northridge, CA (the Valley). Unfortunately, in January 1994, the huge Northridge Quake destroyed the complex. Old age took its toll. Elva relocated to the Garden Terrace Retirement Center, in Vista, CA, where she died in 1997, at the age of 90. She is interred at the Pomona Mausoleum, near her beloved Claremont.