The 1"-wide brass disc with a square hole appears to be from the center of a 50' or 100' windup measuring-tape reel. The winder folds down and locks into the square hole. Various pieces from that type of tape-measure have turned up here in the What Is It? forum many times, but I regret to say I do not seem to have Saved any of the photos which show the complete device.
The other object looks very similar to the nozzle of a blackpowder flask, and it is about the right size to be that. The end of the nozzle is semicircular (like a scoop) to make pouring gunpowder into the musket's muzzle easier. Also, there is one other piece of evidence which MIGHT support that identification... I notice you are in Maryland, where relic-diggers do occasionally find pieces of 1700s/1800s gunpowder flasks.