In the 15 years I've tried to identify this button, my search started with it being a generic Canada Militia button as the first N.W.M.P. buttons were the same as the ones Canada Militia used.
We have some pretty big military guys here that have seen everything and they did not recognize these buttons.
After years, I was expecting someone from out east to know but the ones I corresponded with never saw them before.
All I could find on the Net was the original treaty coat given to Old Sun......
https://commons.wikimedia.org/wiki/File:Treaty_coat_owned_by_Old_Sun,_Siksika,_1877,_detail_-_Glenbow_Museum_-_DSC01084.JPG
It was presented to him by the N.W.M.P. on behalf of the government.
What do the artifacts tell us? Well, all of my buttons were found at Native camps/meeting places. Cam's button up top came " from a site that was used continuously?, or rebuilt upon? through the fur trade."
Now, at Native sites I have also found HBC, N.W.M.P. and military uniform buttons as well.
I.P. was your button found on a site that had a Native presence?
The jury's still deciding but I'm closer to an I.D. now than ever before.
#Edit:
Just found another variation of the crown button (newer?) and a great article close to home......
http://www.mhs.mb.ca/docs/mb_history/48/greatmother.shtml
I don't think I've found that button before but now I better go look through the collection!