In the 3rd and 5th photos. the large blue-ish green object is the forestock cap from a US .54-caliber Model-1841 Springfield rifle, also known as the Mississippi Rifle. Although originally yankee-made, during the civil war it was used mainly by the Confederates. The brass forestock-cap is worth a good chunk of money, because serious civil war gun collectors need that component to "complete" an incomplete Mississippi Rifle that turns up in somebody's grampa's attic.
https://en.wikipedia.org/wiki/M1841_Mississippi_rifle
Free friendly advice:
If possible, go back and hunt the spot where you found that big piece of Confederate-used brass. If a relic that large was there, it usually means a bunch more goodies is nearby.