A bedroll.
A simple bedroll. This can be found in most "explorer" missions in Thief: The Dark Project/Thief Gold and one in both "Precious Cargo" and "Kidnap" in Thief II: The Metal Age. It has no value and produces little noise when thrown.
One notable bedroll is located in the hidden Basketball field in the mission "A Keeper's Training" (on Expert), that secretly is a scroll containing quotes from the development team.