They are all made simply from wrought iron bar with a punched eye. I don't know why the flatter on the left had a rectangular eye. The center one is the sledge hammer head. It does not appear to have steeled faces. It also may have been upset or mushroomed just by use. The swelling or hourglass shape on the right is from both working ends being upset for more mass. That one appears to have the remains of a steeled face.
If you have any clues to how their origin or construction please let me know!