These types of dragons love weapons and armor that have a lot of value (maybe a lot of work put into a sword, a really powerful magic item, or jewels all over the item). I think the very adventure after the dragon hatches, the group will find a dagger. This dagger will be made of complete silver, with a topaz (or some other stone of worth) in the hilt. It will have a lot of work put into crafting it and it will be worth more than another item they have found thus far. It will also be a perfect start for the dragon's horde. That will cause a little problem with the dragon, but i think me players will find the dragon worth more than the dagger.