Chest

There are 3 types of chests: Small Chests, Large Chests, and Golden Chests.

Small Chest
Small Chests usually drop items, but can occasionally drop  and even  items. They cost on the first level no matter what difficulty you're playing on.

Large Chest
Large Chests are guaranteed to drop and  items. They cost twice as much as Small Chests. They cost on the first level no matter what difficulty you're playing on.

Golden Chest
Golden Chests can be found on Risk of Rain (Level), Temple of the Elders, and looping; they are guaranteed to drop a item.