The Clues… In the picture background was a lake.. Lots of water..
The American Southwest.. Hot and dry.
Answer.. Tops for WATER BAGS used keep drinking water cool.
These may have been used in 1908 to 1915 when motor cars were starting to be used by miners in Arizona and Southern California.
I dug these up in an area that had Gold mining during those years. At first, I too wasn’t sure what they were until I found one that still had the canvas bag shreds attached.
The bag stopper was a large cork. To me, these could have been made anytime from the 1850's. When the canvas is damp, the evaporation in dry air kept the water inside cool.
Who made them.. Good question. I have yet to find a source other than the newer “Desert Bags” made by Ames Harris Neville Co.. Sample below. These use a metal closure.
I think "deepskyal" had the best guess for his statement “because the things are tapered in such a way as to keep something from sliding off” was close.
Funniest guess from trikiwi. “paint pots for War paint”
The coin was an U.S. Quarter. (wasn’t very clear)
Now, do you have a mystery item stored away?