You may want to join the discord server https://discord.gg/screeps and ask for help in the #world-help channel. There people can provide in-depth help easily Anyways to give you a brief answer, you'll want to use FIND_TOMBSTONES instead of FIND_DROPPED_RESOURCES. Then filter tombstones with store.* values matching what resources you want. https://docs.screeps.com/api/#Room.find