Bag of Duplication: Put any object that can fit through a 1-foot diameter hole into this bag, and you can draw it back out, plus a duplicate. The duplicate has no value (magical items have no magic, weapons are pot-metal, coins are base metal, jewels are glass, food is non-nutritious, etc.) but they look perfect without a close inspection.

Golden Helmet of Mambrino: This item looks like a shaving basin, but when placed on the head of a paladin, it acts as +2 plate armor. -2 to Charisma, though, since it still looks like a shaving basin.

Bed of Alarm: This bed will instantly wake its occupant if any intruder enters the castle of the original owner. Note that since you don't know where that is, this means it wakes the occupant randomly, any time an animal walks across those ruins, thousands of miles away.

Razor of Logic: At a command word, this razor will instantly and safely shave anybody within 60 feet, except the barber who owns of the razor. (This could be an extremely powerful item, if they learn to use it to shave, say, "the person in this room who betrayed the king".)