There are 28 Memories to be collected throughout the various locations in the dream world. Once obtained, they will be displayed in the Memory Room and appear as a yellow square in the save menu. Each dot/square represents one memory.
After every memory has been found, 7 new items called Empties can be obtained by revisiting certain places.
Memories
Bubblegum
Appearance: A wriggling piece of chewed-up bubblegum.
Location: Found in the Memory Room.
Rose
Appearance: A red rose swaying from side to side.
Location: Found in First Steps.
White Square
Appearance: A hovering white square with a smaller black square inside of it.
Location: Found in White Shores.
Coral
Appearance: A piece of bright red red coral.
Location: Found in the Undersea Expanse.
Umbrella
Appearance: A purple and red striped umbrella with a red handle.
Location: Found in Rainforest Road.
Soda
Appearance: A red soda can with a white stripe down its side and OK written on it.
Location: Found in the Swimming Pool.
Snowglobe
Appearance: A snowglobe featuring a miniature brown house with a red roof depicted inside.
Location: Found in Pink Snowscape.
Beach Ball
Appearance: A white and blue striped beach ball.
Location: Found in Red Sands B.
Cassette Tape
Appearance: A cassette tape dripping with blood.
Location: Found in the Occult Basement.
Balloon
Appearance: A red balloon.
Location: Found in the Monochrome Building.
Sword
Appearance: A silver, pixel art styled sword with a golden hilt.
Location: Found in the Monochrome Building.
Winged Boots
Appearance: A shiny, brown, pixel art styled boot with pink wings.
Location: Found in Cave of Perils.