My wife bought a whistle for me at a local street fair. I believe it was purchased from one of those Appalachian music groups that perform with pan flutes, acoustic guitars, etc…
It is bamboo fipple flute about 11 inches long, only has 5 holes and is pitched somewhere between “B” and “C” (a very flat “C”). The holes are spaced so that you get a whole tone scale. Playing either diatonic or minor is equally difficult but can be done. It has a cool mellow, woody sound.
What is it? Where does it come from? And how do I play a “B” without that sixth hole? I’ve got nothing between “A#” and “C”.
Grover
It sounds like one of those South American pentatonic whistles sold to tourists. If it has a “node or knot” in the bamboo at the end, it is used by the maker to tune the fundamental frequency before adding the toneholes.
You can achieve a flatter second register bell note by using the Basque technique of half covering the bore end hole with your pinky. Reduce the size of the hole with wax/putty for a B bellnote. You can raise the key to C by inserting a thin wooden dowel rod inside the bore to reduce the cubic volume. Each one of the toneholes can be made sharper or flatter by making their diameter larger or smaller(respectively).
Gotcha: banana Feadóg 
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, eh?