Location
Premium areas: Yalahar (Alchemist Quarter, Cemetery Quarter, Magician Quarter, Trade Quarter and Foreigner Quarter), Beregar Mines, on the roof of Cormaya 11, 9 in Tiquanda Bandit Caves, in a cave accessed during the Treasure Hunt Quest, 3 on the ship below Treasure Hunt Island and 5 in the reward room, Treasure Island in this cave, Liberty Bay (Cult Cave) -2 floor & -4 floor (behind piano), Zao Orc Land, below Chaochai, 2 in Zalamon's cave in the western room, 5 in Lower Roshamuul Inquisition camp, several around the Gnome Deep Hub.
Free areas: At the Witch house north of Thais (upstairs here), next to Galuna at the Paladin guild in Thais, in Thais castle (here), Thais west gate in the tower here, Greenshore (upstairs here), next to Thais Lighthouse (here), and possibly more locations.
Notes
You can use one crate per hour to get an item. It's also possible to get nothing at all.
If you do get something, it will be one of the following:
80 Gold Coins
Mana Potion
Heavily Rusted Legs
5 Ham
Heavily Rusted Armor
Dwarven Ring
50 Gold Coins
5 Brown Mushrooms
Health Potion
Looks the same as a Crate, an Old Crate, a Crate (Wine), a Crate (Swapped), a Crate (Jimmy), a Crate Full of Coral, a Machine Crate and a Weapons Crate.
You will receive the achievement Free Items! after obtaining 50 items from crates.
See also: Crate (Usable)/Statistics