https://chaoscode.io/resources/buried-treasure.118/
This plugin spawns treasure maps that a player can use to find hidden treasure around the map. The maps spawn in pretty much any loot source.
When a player finds a map, they can move it to their quick bar, press the number of the quick bar slot that the map is in and click the right mouse button. DO NOT CLICK ON THE MAP ITSELF. This action will remove the map, tell the player in chat what grid location the loot is in, then mark their in game map with a “Lootable Crate” icon ONLY THEY CAN SEE. The crate can spawn anywhere on the map.