[size=medium]Glad I could help without even being in the field detecting yet as a "newby"!!! The brass piece appers to be a shell casing, percussion cap type piece, not sure, however the two brass pieces with the turn keys on them are antique Gas Lighting turn off valves, the one is very nice with the spade shaped leaves on it, I would check it carefully for a name, NICE FIND! The other valve is somewhat common, meaning for that style valve but both are from the 1800's, they good date back well into the 1800's. The curved piece with the threaded end is also an antique light part but looks like the other end may be damaged, they also made some that resembled the light parts for hat or coat holders, not knowing the size it's hard to say, also from the 1800's. Don't know about the round thing in 3rd photo lower right. The bell thing have anything inside of it such as a place to hold a dinger or "clapper"? If not I would GUESS another lamp part, possibly a candle snuffer end from a brass rod as I see the one end looks threaded, possibly from a church. Hope this helps!
P.S. You have hit a great spot! I would hunt it well as the one valve good date back to 1850's! Most American homes started switching from gas to electric in the late 1800's, keep digging![/size]