In The Elder Scrolls V: Skyrim, some barrels are called thief caches because they are used by the Thieves Guild to hide weapons, lockpicks and other resources their fellow thieves may find useful. They only appear after a city influence quest has been completed there.
There are two types of barrels that can be found in most locations. Most barrels can be searched; however, there is one variation that cannot be. Barrels usually contain vegetables, such as carrots, cabbages, potatoes and other edible items. Barrels usually respawn in 48 hours, removing anything placed in them and restocking its inventory. Barrels found in owned locations and a few shared shacks will not respawn items.