Here is the full list of all 48 Where the Wild Things Are achievements worth 1,000 gamerscore.
Find 95 Stars
Collect all Geodes
Collect all Seeds
Cause three different Wild Things to sneeze
Collect all Turtles
Collect all Honeycombs
Complete a Sailing mission without crashing
Complete the game on Easy or higher
Complete the game on Normal or higher
Complete the game on Hard
Complete 'A Trip to the Moon'
Collect all Houses
Collect all Skulls
Earn 10 Hearts
Collect all Owl Eggs
Complete 'Below the Roots'
Collect 25 Turtles
Complete 'Setting Sail'
Find 65 Stars
Collect 25 Geodes
Complete 'Old Willow'
Complete a ride with Carol without crashing
Be eaten by three different Wild Things
Start a Dirt Clod Fight with multiple Wild Things
Complete 'Crumbling Island'
Collect 25 Owl Eggs
Collect 25 Honeycombs
Complete 'Rebellion'
Allow three different Wild Things to fade into oblivion
Find 40 Stars
Collect 25 Seeds
Defeat 25 Lightning Bugs
Earn 7 Hearts
Defeat 100 Shadow Creatures
Complete 'Seasick'
Complete 'Canyon River'
Complete 'The Cave'
Find 20 Stars
Defeat five enemies with one firefly bomb
Defeat 250 Fireflies
Complete 'Road to Nowhere'
Earn 4 Hearts
Collect 25 Houses
Complete 'Arrival'
Find 5 Stars
Defeat 15 enemies in a row in melee without being hit
Power-swing from three bars
Collect 25 Skulls