One way of generating interesting treasures, especially when it's a powerful monster, is to think about what's important to the monster. What kinds of things might a dragon really need? If the answer is that, hey, maybe this one needed a laxative recently ... pity the adventurer who misuses that barrel of pink potion in the lair. How do guy dragons make themselves attractive to the scaly sirens at the saurian singles bars? Is there a bucket of scale-shinola in the lair's hidden compartment? Maybe that stuff actually strengthens metal armor (or leather armor) for short periods of time.
And do dragons have pets? A pet and some pet supplies would be interesting stuff to find in the dragon's lair. Watch the characters take really, really good care of that cockatiel until they can figure out what it "does." Negotiating with a dragon that wants 40 pounds of mixed seeds?
The most recent bit I wrote this morning was about a monster that eats brains. In the treasure hoard? A long-handled gold spoon...
Vickers Medium Mk.III update
7 hours ago