You died while mining in lush caves, but little did you know that you were being stalked the whole time. All those glowing berries that were hanging from the ceiling and swaying back and forth weren't from the wind in the cave, but rather from the thing following you.

The Knocker watched as a creeper snuck up to you before exploding, ending in you dying and loosing all of your stuff, or so you thought, because The Knocker took them right after you died.

After respawning in your house, you made your way to the front door so you can go back into the cave because you weren't just going to lose all those stuff, but after opening the door, your stuff were there. Not all. But they were there. It was obvious that whoever put them there has claimed something as theirs, nothing valuable, just personal.