FOR $36, THE Little House Bookstore in Mansfield, Mo., will send you an "I Love Laura" tac pin, a "We Love Laura" pencil, a Laura doll and posters of the "Charles Ingalls family." Or perhaps you'd rather shop at the Wilder Museum in Walnut Grove, Minn. There, for $32.40, you can get Little House cookbooks, a thimble with an ox and wagon on it or a toothpick holder in the shape of a milk can.

I know this because a friend, knowing of my odd devotion to Laura Ingalls Wilder, even at the advanced age of 28, recently sent me brochures that she had picked up on a trip to the Midwest. I probably told her that on a shelf within easy reach of my bed, I still have the beaten paperback copies of the "Little House" books that inspired a television phenomenon and much more. My name is inscribed on their inside covers in my 8-year-old handwriting and I pull them out to read whenever I have trouble sleeping.

But now that is all changed. The Laura Ingalls Wilder I grew up with is no more.

My disillusionment began with a book published last spring, "Ghost in the Little House," written by a University of Missouri professor named William Holtz. The thesis he poses is this: that Laura Ingalls Wilder was dependent on her daughter, Rose, as a ghost writer for the "Little House" books.

Holtz does his best to explode the myth of Laura, at age 63, sitting down at her farm kitchen table and producing those volumes. In penciled longhand, on nickel tablets (so goes the myth) she turned out tales of a feisty 19th-century pioneer girl who loved to ride horses, helped her pa make hay by trampling down dried prairie grass with bare feet and hated sewing button holes.

The myth had -- and has -- tremendous power. As a kid, it was always terribly important to me that a girl named Laura grew up to write stories about What Really Happened. I remember the winter when the trains couldn't get through the snow and the family nearly starved. I also remember when Laura got in trouble for writing a nasty rhyme about a teacher, and when she rode behind horses that her pa thought were too rough for her.

The Ingalls family's adventures were a primer for someone like me, a suburban kid whose grandparents came over from Eastern Europe on a boat. Holtz himself remembers telling his daughters that when they got into a difficult situation, they should "try to think about what Laura would do in a similar situation." The "Little House" books describe a classic American story: the conquest of the West.

The thought that Rose had a hand in this -- and Holtz's book does a good job proving tht she did -- might not matter much unless you consider who Rose was. Rose was not Laura. She was, rather, a novelist and a journalist who traveled the world and hobnobbed with the likes of Dorothy Thompson, Sinclair Lewis, Clarence Day and Max Eastman. She divorced young and had a series of lovers. She corresponded with Herbert Hoover, covered the Vietnam War at age 78 and amassed an FBI file for her libertarian political activities.

Learning about Rose's role in shaping the "Little House" books is like being told that Grandma Moses' paintings may have had a workover by Andy Warhol. Even if you still like the paintings, they mean something entirely different. When the Holtz book was published, quite a few newspapers picked up the story. "Mother-Daughter Question Stirs Up Raging Prairie Fire," read a headline in the San Antonio Express News. "Little Lie on the Prairie Confirmed by Roommate," said the Columbia Missourian. Friends of mine echoed this alarm when told the news. "Why don't they leave her alone!" cried one. Another, practically whimpering, said, "He can't have any really good proof."

What Holtz has termed the "Laura industry" is none too happy. From Iowa to Minnesota to Kansas, at every stop of Laura's family's journey west, Laura aficionados have set up museums and historical societies in her image.

The Laura Ingalls Wilder Society in De Smet, S.D., gets 25,000 visitors a year from 35 foreign countries. Besides maintaining surviving buildings and sites, the society boosts the local economy by keeping high school and college students employed as tour guides.

At Walnut Grove, Minn., where the Ingalls family lived in the mid-1870s, tourists can visit a museum, swim in a lake called Lake Laura and camp nearby at one of 40 sites with electricity and showers. They can also see an outdoor pageant called "Fragments of a Dream," selected as one of Minnesota's "top 25 festivals and events." According to a brochure, "Hydraulically moved sets, special technical effects and modern light and sound systems add to the professionalism of the production." A month ago, a Japanese television station held a contest and then sent 20 "Little House" fans on a trip to Walnut Grove.

The folks who run these places speak of Laura and her family as if they knew them. "We have the surveyors' house here. When it got real cold, during '79-80, the surveyors said that Pa could stay at their house for the winter. In the spring, of course, Pa filed on a claim," says Vivian Glover, director of the Laura Ingalls Wilder Society, describing an attraction -- and recalling an episode I know by heart from "By the Shores of Silver Lake." Their way of talking is infectious -- I had to stop myself from chiming in with, "And Laura was so happy when they sat down for dinner and Ma gave them canned peaches from the surveyors' pantry."

When it comes to talking about the Holtz book, though, they become less chatty. When I asked the Walnut Grove museum director, Shirley Knakmuhs, about "Ghost in the Little House," she read to me from a letter written to her by Roger MacBride, the adoptive grandson of Rose Wilder Lane:

"{A} professor at the University of Missouri has put out a book with the sensationalist title of 'Ghost in the Little House' . . . . {I}n my opinion the book can only serve to disappoint children who read the 'Little House' volumes. I certainly would recommend that you give serious consideration to not handling the book."

"From what I understand," added Knakmuhs, "all the manuscripts are in Mansfield, Missouri. That is proof itself that {Laura} wrote the books."

Perhaps. The museum in Missouri does have some of the nickel-tablet manuscripts. And it is true that Holtz's main documentary evidence, besides Rose's diaries, is a close analysis of only one book -- different drafts of "Little Town on the Prairie."

But listen closely to Laura advocates and it soon becomes clear that they argue more with passion than with facts. Nobody actually denies that Rose helped with the books. It's Holtz's sharp language that they object to. Rose didn't ghostwrite the books, they insist -- she simply "helped" or "collaborated." Roger MacBride, who originally cooperated with Holtz but later withdrew his approval, chastises Holtz for his "cheap title" for a book that is "99 percent about Rose." Yet MacBride agrees that "Rose put in a sense of pacing and timing, rearranging the sequence of events." Norma Lee Browning, who lived with Rose in her later years, told the Columbia Missourian that Holtz had taken a "cheap shot" and that Rose had simply "collaborated" with her mother. She added, however, that Rose didn't want Browning to talk about Rose's role in shaping the books. "She told me, 'You are not to discuss these 'Little House' books with anyone!' "

Holtz's portrayal of Rose, through interviews, quotations from Rose's diaries, letters and other papers, show a woman who is used to writing for a living -- literally. The more she wrote -- and she wrote over a dozen books and countless short stories -- the more she got paid. Only in the beginning of her career, as a journalist in San Francisco, did she actually draw a salary. Rose's mentions of her mother's books show her complaining about the extra work she took on in editing them, but also a sharp sense of their commercial value. She knew that the illusion of Laura's sole, unedited authorship was good for selling books -- and selling books was important.

Roger MacBride certainly understands the commercial side of the legacy. The popular NBC television series, which ran for nine years in the late 1970s and early '80s, was his idea -- although he and a partner pulled out when it became apparent that Michael Landon's vision was not exactly driven by authenticity. Now MacBride is coming out with a new book, "Little House on Rocky Ridge," which follows the pattern of the "Little House" books, but tells the story of Rose's life -- beginning when her parents, Laura and Almanzo, settled in the Missouri Ozarks. The book is to be the first of a series that follows Rose through her childhood on the farm and on to her first taste of the big city, when she lived with her aunt in Louisiana. HarperCollins has printed 450,000 copies; it has been bought by the Book of the Month Club.

The Rose described by Holtz probably would have approved wholeheartedly, provided the new books met her literary standards. Why not continue the commercial venture of "Little House"? Maybe the next generation of kids will warm to her story, another American classic: the escape of a farm girl into the great, wide world.

The truth is, I'm looking forward to them myself. With disillusionment comes enlightenment, and while I may have lost the Laura I thought I knew, I have gained Rose. In "The First Four Years," the last book in the "Little House" series -- and the only one that Holtz credits entirely to Laura -- Laura recounts her daughter's birth: "A Rose in December was much rarer than a rose in June, and must be paid for accordingly." Knowing about Rose is worth the price.

Nancy Watzman is a Washington writer.