"The Southwest Arkansas Toothbrush Museum"
This one is in the town of Hope, or close by. This one is a joke, of course, since there aren't any toothbrushes in SW Arkansas. Apparently there was ONE tourist who left one in the motel when he left. That's the one that is in the museum. Odd, that two presidential candidates have come from Hope, Arkansas, in the past few years and both of them were governors of Arkansas before they ran for President. One of them actually made it, but his wife ran the country while he sat in his office and smoked big cigars.
"Museum of Camouflage"
Once, while driving through the wilds of southern Missouri, not really as far from Hope as you might have imagined, I stopped off at Fort Leonard Wood specifically to see the U.S. Army's famous Museum of Camouflage. The building proved too hard to find, though, so I finally just left, my curiosity unsatisfied. It wasn't THAT much of a disappointment since I have seen camouflage before. I think.
Also in southern Missouri (I think) is the "National Chainsaw Hall of Fame Museum and Pigsnort Indian War Memorial." A twofer.
We don't have Route 66 going through there (officially) anymore, so you won't find that many snake pits or large balls of string anymore. However, if you are willing to travel a few miles off I-44 near Joplin, I once stopped at a flea market there where there was this guy in a white flannel suit who, for $15, would let you spit on him. No museum, though.