I agree with a lot of suggstions that others made earlier in this thread.
Especially flowers[W]
But I have other suggestions too.
A new Building type called Mining Shaft. Maybe that should be something only available for dragon lairs. Purpose of that type is to spawn Metal, Gems or stones. Available in T1-T6. The spawn should below enouthto notsupport power leveling. Maybea max of 5 nodes per material, respawntime around 1 hour.
Farmland structures. Different structures to hold cows, chicken and sheep. Different structures for fields of flax, kenaf, cotton,... grain, grape, carrots, rice and so on.
Dryad house style. A large tree with a chamber in it or something like that.