Some of my ancestors rode with Captain Quantrill. I have been studying Missouri Partisan Ranger movement in 1860's Missouri for 35+ years - and I will tell you this is a pure pile of crap !
Quite simply put - A fantasy piece.
Firstly, Quantrill's men mainly used captured M1859 McClellan saddles. Theoretically, the faker of this piece wants the buyer to believe that Quantrill's men simply popped off the US saddle shield / plate - and then placed these on the pommel crown of the saddle in place of the original M1859 McClellan pommel shield. Very laughable.
Quantrill's men would have NEVER made such a plate to give themselves away to the enemy, as they rode right through and even stopped, drank and spoke with Yankee soldiers when doing reconnaissance. My gosh, would it make sense to advertise you were the enemy? Especially with a "No Quarter" martial law effected against Quantrill's men. Think about it....
Also, the majority of Quantrill's men formed in 1863 ! NOT 1862 as indicated by this plate. Phooey. This joker who made this plate needed to do his homework !
Unsure of time and place of production, but is absolutely a non-piece of history and oft seen on FleaBay.