Cricket Pie: Return to the shop in Mushroom Kingdom when you beat Croco.

Alto Card: Complete first melody in Melody Bay.

Bambino Bomb: Beat Croco the second time.

Tenor Card: Complete second melody in Melody Bay.

Room Key: Pick up the key in Boosters Tower (the room with the bombs)

Elder Key: in the Booster Picture room, flip them in this order: 6,5,3,1,2,4

Cricket jam: Find in kero Sewers after going through lands End.

Temple Key: Talk to the Thwomp in Monstro Town 7 times.

Soprano Card: Complete third melody in Melody Bay

Big Boo Flag: Look between the O and A in Yosters Isle.

Dry Bones Flag: Look under Marios Bed in Marios Pad.

Greaper Flag: Look behind the rose town welcome sign.

Game Boy: After you save the princess, go to Mushroom Kingdom and buy the Game Boy from the guy in the inn.

Catsle Key 1: Get it from the guy in Nimbus Catsle.

Catsle Key 2: beat Birdo.