Dead Heads was a former plugin that allowed for easy gathering of player's heads.
The plugin is rather simple. Every time that a player dies in MC, instead of breaking into a lot of items that can be easily gathered by the players walking around, the body disappears and a head takes it's place. The head that appears will be of the skin of the MCplayer at that time. If you break the head you will receive a skull named player's corpse. It is a skull, not a player head. Beware, breaking the skull will delete the inventory of the dead player. The head also disappears after 5 minutes, so in battle, one has to decide fast what to do.
The inventory is connected to the head of the player who died. To access it, simply right click the head and await about 10 seconds for the inventory GUI to open and move the items you want, leaving the ones you do not. Doing this in the middle of a battlefield will be dangerous, as you need to wait to get the inventory, and then make the switches. The inventory will disappear after 5 minutes together with the head, and will also disappear if the head is broken.
Killing a player creates a player head instead of dropping items. Right clicking the head accessed the inventory. Breaking the head to receive a player skull, this destroyed the inventory. Head and inventory disappeared after 5 minutes.