Metal buttons are widely used in the garmetn industry. In order that the metal buttons of one manufacturer be competiteve with those of other manufacturers, the buttons customarily are stamped as shells out of sheet metal and provided withthread receiving holes. A peripheral lip or flange on the shell gives the button thickness and a degree of rigidity. In many instances, however, because of puckering of hte material, they are made flat or concave in an attempt to minimize the puckering.

While metal buttons can be inexpensively produced int he manner described above, when they are attached to the fabric of a garment by an automatic sewing machine the thread is thghtly drawn around and into engagement with the edges of the holes in the shell. As a result the fabric is drawn up into the shell producing an unsightly pucker. In addition, the engagement of the thread with the sharp edges of the hole may result in undue wear on the thread and possible loss of the button.

Some attempts have been made in the prior art to solve the problem outlined above. Perhaps the most significant of these is the manufacture of a two-part metal button comprising an upper shell provided with thread-receiving holes and an undershell provided with thread-receiving holes and adapted to be assembled with the upper shell to form a button.