It could be brain tanned leather with mother of pearl pieces. Looks like Lazy Squaw stitching but not sure from here. Could be West coast.
We have a lot of Native things here in New Mexico. In my experience a professional appraiser is the way to go. And BTW ask for cost because they can be miles apart. I once had three pieces appraised. One wanted $250 for each piece the other charged me $49 for all three. And he was well established.
From here it doesn't look as if it has been used. That could affect it's value. Look for a signature or mark. That would be a later piece.
You can probably find the markings on the net. There are a number of sites for that.
Anyway it goes it is a lucky find.