I am fond on the “weathered paper” trick for paper handouts. I use that one often.
I’ve used the tarroka deck when running Curse of Strahd, and the Harrowed Deck for some Pathfinder games.
I’ve used an old camping lantern to create a mood during a creepy game once.
I’ve purchased some campaign coins before and used them for currency but I never seem to have enough to represent the collected treasure the group finds. So I just use the “pouch of coins” and toss it to the players when they get paid for their work.
Along the same line, I purchased a pack of plastic pirate coins from Party City. Great to represent treasure or to use as bennies/tokens.
Invisible Sun came with a wicked creepy hand (see below). I haven’t run the game yet but I can’t wait to set that in the middle of the table.
I am quite fond of medallions (see below, ignore the one from Pirates of the Carribean, that hasn’t been in a game yet). I have quite a few I have collected over the years.