Not much for dragons to farm, huh?

It seems like the only items you can level up by having dragons farm are Dragon Tree, Hill, Living Stone, Mushroom, and Water. I've already shared the end rewards for maxing out Living Stone and Water. For the Hill, I'm just short of max level, so once I merge it to the highest level, I'll share the rewards soon. Once Dragon Tree and Mushroom are also maxed out by dragon farming, I wonder if there's anything else to have the dragons do. Crystal Flower or Bush require more than just dragon farming; they need to be done in conjunction with other items (like Undead Tree). Life Flower and Fruit Tree are a race against time that can be done without dragons.. Dragon Houses, Brick Warehouses, and Coin Banks do require dragons, but I don't expect any particularly fun reward events from maxing them out.. Anyway, I'm leveling them up because I'm looking forward to the events when items reach max level. When I'm doing tasks unrelated to dragon farming, it's annoying when the dragons wake up and just wander around aimlessly, lol. Is there anything else I can have them do?