I do not know if an item that was dropped and then picked up will go to where it spawned or where it was dropped.
I do not know, but I assume that logging out and in will make it so that your thrown stuff does not disappear.
I made a video, the 2 left columns are from another server and the 2 right columns are from that server. The crowbar was from that shed.
https://www.youtube.com/watch?v=7wpTz0zpoGI
the stuff on the left gets thrown, the stuff on the right disappears. I do not know why the tomato didn't disappear.