World 1 (Yoshi's Woolly World)
From the Super Mario Wiki
World 1 is the first world in Yoshi's Woolly World and Poochy & Yoshi's Woolly World. It is a grassy plain with small forests. This world has nine levels: eight compulsory, and one optional special level unlocked after collecting all 40 Smiley Flowers for the world. Completing this world unlocks World 2.