A three-piece set, including a quilt, dust ruffle and fitted sheet retails for about $80.
The bottom sheet is called the fitted sheet.
In some versions, such as a bed-in-a-bag style of comforter set, in addition to the comforter and sham, you may also get one (perhaps two) pillowcases, a fitted sheet and a flat sheet.
The set includes a queen size comforter cover, a flat or fitted sheet and two standard pillowcases.
The Dora toddler sheet sets include a flat sheet, a fitted sheet and a pillowcase.