Did you find a fossil that you no longer have due to trade, selling or donating and now wish that you had it back?
Here is a personal find if mine, that due to changing "likes" in the fossil world, I sold to acquire other fossils that were of interest to me at that time. The rarity of the fossil did not matter much because I had other fossils that were just as special. Now my interests have been renewed in my Mazon Creek finds and I wish I had it back- at least I have a picture of it.
The Mazon Creek Onychophoran "Iloydes inopinata"