I dropped a backpack on the ground, full of items, while being crouched in a tall yellow bush. The backpack teleported on top of the bush and from that point it was unreachable. You cannot interact with the backpack in any way because it's too high up. After trying everything, I finally got my backpack back by making a fireplace, dropping it on the same spot and standing on top of it.
This has randomly happened to me with pretty much any item, but the backpack seems to go the highest.
Just drop any item on the ground while in a bush.
The fireplace (when dropped in a bush) seems to float only a bit above the ground. This allowed me to step on it and finally grab the backpack, which was floating much higher. This may potentially be used to get into bases, over fences, or into other unreachable places, but I have had only relative success reproducing the bug. It 'worked' 2 times out of around 20.
Forgot to mention that after cutting the bush down, the item stays, floating where it was.