Free IKEA Sniglar bed and mattress (missing safety bar): https://www.ikea.com/us/en/p/sniglar-bed-frame-with-slatted-bed-base-beech-s19185433/
Perfect for after crib before twin bed and a small room. Since it is from IKEA you would need to purchase their sheets to fit or you can use twin sheets and tuck the excess.