So working on my one page dungeon full of semi intelligent golems, and came up with a trap to really stick it to those air breathers. The characters are going to be hungry because the trip to the dungeon is a few days. When they step into a room on the second level and see a harmless fruit bowl sitting on a table they’ll be tempted. To try a bite and then blam the fruit bowl trap activates.
The individual fruits in the large bowl begin to wiggle about and burst open to reveal tiny bug like golems. The fruit bowl trap acts like a swarm that gets a surprise attack on each player in the surrounding squares first turn in. You could treat the swarm like a spider or centipede swarm.
Have you trapped any mundane items in your dungeons recently?