From what I've seen so far, you can't get any curiosities from building objects except for indirect things like wonderous wood shavings and roots when collecting materials. How about some curiosities from building things, especially those with lots of small pieces like walls, so we can gain LP doing those tasks. People will be able to gain LP constructing and building their town instead of being forced to stock pile foragables before hand.
An idea for an item would be something like "loose mortar" that you would get rarely from building brick walls or stone mansions.