Your fancy suspenders-adjuster buckle is from Guyot suspenders, made in France in the late-1800s through early-1900s. You can see it in the 1907 advertizement showing the form of the Guyot suspenders, below. (Click to enlarge the image.)
The French word "depose" stamped on it means something like "guaranteed genuine."
I think your rectangular buckle is upside down. It looks like a bunch of grapes flanked by grape leaves. That's all I have right now.