Here is the full list of all 18 Dragon Creek achievements.
Own 20000 gold
Train your first dragon to Rank C
Train your first dragon to Rank D
Get a classic to S Rank
Get a wyvern to S Rank
Get a lung to S Rank
Get a cat to S Rank
Collect 100 dragon poops
Train a dragon to 999 in every stat
Own 5 S Rank dragons
Train your first dragon to Rank B
Train your first dragon to Rank A
Own 99 cakes
Get a hydra to S Rank
Get a perfect score in every training game
Get a nightmare to S Rank
Get a dino to S Rank
Own every food item at the same time