KidSnide
Adventurer
I do a fair amount of larping (don't talk about it much on ENWorld since this is generally a tabletop board), and calling something a "prop" makes me think of larping instead of just adding some items to add flavor and feel of a tabletop game, which made me think of the old Infocom games and the pack-in "feelies" used to add atmosphere to a text-only game in lieu of graphics.
Then again, that is just me and my quirks and the fact I tabletop and larp regularly.
I've played in dozens of LARPs too, and I would call these things "props" because that's what they are. Creating a letter or map for a table-top game isn't really any different than creating it for a LARP.
"Feelies" is a term I hadn't heard until this thread. It sounds creepy, and not in a good way...
-KS