Chests
Some village zones include a village chest in their exploration drop pool. Konoha, Suna, Kiri, Kumo and Iwa each have their own chest with rewards themed around that region.
A chest is not awarded just because you completed /explore. It must be available in the selected zone and then pass that zone's drop roll during one of your exploration events. Use /village zones and open the zone details to check the drops Kakashi currently shows before you spend time farming there.
When you find one, it is added to your inventory like other item findings. Use /item info if you want to inspect an item before using it.
Treat chests as a rare bonus, not as the baseline reward from exploration. Pick a zone whose ordinary materials are useful to you as well, so an unlucky run still advances something you need.