I've seen several whose hooks are still intact. Definitely made for attaching "permanently" to thick leather ...not like a buckle's hooks, which allow easy removal from the leather.
Unfortunately, I've never seen one of those objects still in place ON the leather (which would tell us exactly what they were for). I've thought of them as being more Ornamental than functional objects, because merely "functional" objects which have a plain face usually aren't silverplated or goldplated. (The additional expense of plating with a precious metal is usuaully reserved for Ornamental/Decorative objects.) That being said... due to the distinctive form of attachment-hooks and the object's peculiar shape, Duggap may be correct that they are a strap-tip. In view of their small size, they might be from something like a "fancy" saddlebag's leather straps.