S1·E256 A Lost Thing of Smiles!

Laura and her classmates go on a field trip to a flower garden with Mr. Yoshi, and the Ham-Hams tag along. When they get there, the place is covered in trash! Both the students and the Ham-Hams help to clean up the garden, but Laura loses her pendant that has her feelings for Travis written inside. So Hamtaro tries to get it back to her before Travis finds it.