Instructions
Use paint thinner on Clarabelle's lawn, the first flower will be inside the pit that forms there.
Head to the cave that lies between Clarabelle's house and Ortensia's house. Use the thinner on the walls inside the cave to uncover the second flower.
Travel to the Gag Factory, and use the paint thinner to search the adjacent walls. One of the walls contains a cave, and inside the cave is the final flower.