Two sessions ago my players found some strange wooden tokens on a 3D diorama of the forest they have been exploring. These tokens were moving independently of any force they could discern. The players threw them in their packs and hoofed it back to town to pawn their loot. It took every ounce of restraint to stop myself from shaking one of them and screaming, "FOR THE LOVE OF GOD DO NOT SELL THESE."
But I didn't. I just quietly smirked as they they traded a set of magic tokens to the vendor for a stack of gold without even bothering to identify them. To be fair, my players were in rough shape. They had recently lost a fight to some bats (food, as one of my players called them) and had very little in the way of cash. Even if they knew what these things could do, they likely still would have sold them to fund their next trek to the caves below Fyndel Forest.