From the Super Mario Wiki
Trashures are brown Treasure Chests that appear in Mario & Luigi: Bowser's Inside Story. They reside in Dimble Wood. Their name may be a pun of the saying "One man's trash is another man's treasure" or a pun on "trash" and "treasure". They attack by opening their bodies, and having the lock on them throw either a Scutlet, a Hammer, an iron ball, a Coin or a Mushroom at Bowser. They will throw three to five random items. If countered, the object will fall back on to the Trashure, damaging it if the object thrown is one of the first three items. The hammers from Trashures can make Bowser dizzy.
If the lock is significantly damaged, it eventually falls off, which makes the chest open, exposing the treasure to Bowser's Vacuum command, which sucks the coins out of the Trashure, defeating it at the same time. If the player does not defeat these enemies within a few turns, the enemies will run away, hopping off the screen. If they run away, the player does not earn any Experience Points for battling it. Mario and Luigi, having no access to the Vacuum command, have no choice but to simply keep attacking it until it is defeated.
Trashures have a stronger counterpart in the Fawfulized Princess Peach's Castle, Dark Trashures.
Names in other languages
|Comes from the English "treasure." May also be derived from 「じゃん」jan, meaning "isn't it?"
||From cofre (chest) and fraude (fraud).
||From cofre (chest).
||From "coffre-fort" (safe, "coffre" also means chest) and "fou" (crazy).
||From "coffre-fort" (safe, "coffre" also means chest) and the familiar word "fortiche" (clever)
||From Schatz (treasure) and Fratze (antic, mug)
||Scrigno means "chest" and Maligno means "evil".