New players may not know the link between the Items option at the bottom, and the inventory lists at the top of the screen. This video should help clear up the mystery. Each is a good way to see what resources are available and placed in reserve so they can be claimed as needed. It is also a good way to find what the clan has been giving through claimable chests and chests that came with any packs you have purchased. The purpose of putting resources in reserve is so when your city is attacked, the resources won't be available for claiming and so you can add them to your active inventory when you need them. There are more details provided in the video, but there is also more to show in the future.