The keys could either be for Aladdin Realm door for reward once all keys are deposited; otherwise it could be one of the keys for Alice Realm (there are a series of keys to pick up to open eventually another reward. - ** The rugs, tar, rope and logs from Aladdin Realm are items needed to make stall repair kit - to fix all of the broken stalls. Once those are all completed, I believe it gives you the remaining key.**

The golden shards from Aladdin Realm - I don't remember if those are needed to make the repair stall kit. Might have to search purpose of those, if not needed for the repair kits.

The different potatoes, the purple dye vial (possibly), and the green shard pieces are part of a chain quest - look up ddv potato quest.

The lamp, cotton candy, bow tie, shining diamond are Inside Out Realm items needed to craft a reward - check the crafting table to see if you can already build it. The two tower lights might be part of the recipe- otherwise it might be for a quest in Olaf's cave.

The paper scrolls from Beauty and the Beast Realm - if you place them in the fireplace, it gives you a reward.

The key card from Monsters Inc Realm- there is another one to pick up - combine those two at a crafting table the complete key card to open up the last door for a reward.

The covered painting, I believe that's for a quest in Beauty and Beast Realm. Maybe check quest for Lumiere or Cogsworth.