What You Lie on in Bed
Puzzle 18 of Alliteration Piece of Cake Pack
Question is: What You Lie on in Bed
and the answer is: MATTRESS
Word Meaning:
MATTRESS — A pad on which a person can recline and sleep, usually having an inner section of coiled springs covered with foam or other cushioning material then enclosed with cloth fabric.
Definitions from Wiktionary.