Shrinkstools are a powerfully enchanted toadstool, typically found in enchanted forests or other secluded magical locations. Watch your step.
The Slow Death Cap looks, to those who don't know what they are looking at, like an edible mushroom, but eating it is one of the most unwise things anybody could possibly do.
Pirates' many bejeweled rings and piercings actually had a practical purpose - when the pirate or sailor died, the rings could be taken off as payment for a proper burial, saving him from a watery grave. This could be tied into regional culture, or made into a quest (The Pirate's Lost Rings, etc.). Also gives treasure-seeking divers another thing to look for besides crusty old chests.