Moving DD into a twin size bed and need a mattress only (no box spring). One of her friends at preschool is moving and the mom wants to get her kids an organic mattress and looking to get rid of the others. She has a twin Sealy Posturepedic Preferred one-sided mattress that she said she would give me for free! She mentioned it has been barely used (her child will turn 4yrs in Dec.). She isn't a close friend, but our kids have had a couple of play dates so she isn't a complete stranger to me. My husband and I are on the fence about getting a "used" mattress for our DD for hygiene reasons, but not sure we are overthinking it. What would you do?