Dog Collar exists for people who had it in a display case. It doesn't show when you open the inventory, and will vanish if the case or camp are ever scrapped or stored. Any that were in the player inventory or stash vanished when they patched them put. They only exist as an animated item in "legacy" display cases.

The Bolton Greens pieces you were talking about in the other thread can be kept still. So can the Mama Dulce items. The Distinguished Guests items can be dropped and traded, the 3 Feed the People items cannot. Those will give the "this item will be destroyed" message.

The Mysterious Component item you have is one of my wishlist items on PS4. It's awesome on display, I only ever saw one of them in a camp and never even negotiated a trade despite asking on the sub multiple times with big offers. Not many bugged. That one is rare af.

The Mama Dulce and Bolton items, and Project Paradise too...either pick up extras during the gathering portions and spam the drop button or store (in a random container, desk, locker, etc) right as the event/segment ends, OR try to pick them up at the very end of the event...after the completion animation appears but before the item vanishes.