An amulet of bounty is an opal amulet enchanted via the Lvl-1 Enchant spell.
The amulet begins with 10 charges. When equipped, there is a 25% chance to save seeds when planting them in allotment patches, consuming 1 charge. After all charges are used, the amulet will crumble to dust.
Similar to a ring of recoil, amulet of bounty charges are stored per player, not per amulet. Thus if the player sells or casts High Level Alchemy on an amulet with 1 charge remaining, the next amulet the player equips will still have only 1 charge. The player can right-click to "break" an amulet of bounty, destroying it and restoring the next amulet of bounty the player equips to 10 charges.