Nice find! I'll take a stab at it, I don't recogize the "medal" or Badge (Award?) but from the age I'd say 1890's or perhaps later (ww1?) based on some clues; First look at the eagle atop, that sytle of eagle is post Civil War and likely post "Indian" wars" Second look at the STYLE of the crossed rifles, although they are not that clear it seems to me that they might be bolt action rifles and the US army didn't use that type of rifle until the 1890's. Third look at the crossed sabers, that represents the Cavalry. The US Cavalry was a component until sometime around the 1920's, phased out by Armor. Last, every major Component Corps of the US Army is represented on that insignia including the Corps of Engineers (Castle) and signal Corps (X'd Flags at top) all of which were formed during the Civil war and better established in the later 1800's .
You might try researching by googling "History of US Military insignia"