From the Super Mario Wiki
Petal Guys (originally known as Mufti Guys) are Shy Guys in Super Mario World 2: Yoshi's Island, Yoshi's Island: Super Mario Advance 3 and Yoshi's Island DS. They wear flowers on their head and use them to hide by crouching down on the ground so that Yoshi can only see the flowers. When Yoshi gets close to where they are hiding, they will get up and try to hurt Yoshi. When they get up, they still have flowers on their head.
Petal Guys return in Yoshi's New Island.
Names in other languages