Mystery pin

[TNBBNAYLOR]

I found this pin yesterday metal detecting along with the 1901 barber quarter it is in top of. I think it says:

1938
Kpsc
1800

I think it had a pin type of thing on the back but it isn't there now. If you know what it is or what Kpsc means please comment

 

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Here's one for sale on eBay here: Mystery Star Pin Vintage School Company Society 1938 KPSC Member Collectors | eBay
They don't know much about it either. The characters under KpSc is the bottom part of the 1938 numbers.