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.
Additionally, there are 7 items called Empties that are hidden throughout the dream world, typically found through invisible pathways or unorthodox solutions. Unlike Memories, they will not be displayed in the Memory Room and instead appear as a black square with a purple border on the save menu.
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. If the OK Lemon poster has been viewed in Dream Chicago, then the soda can will be yellow.
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.