Charles I half groat

Edward I

Clipping:

Early coinage was made of silver and it wasn't until 1697 that milled coins were seen in general use, before then coins were handmade and stamped.

The reason for milled coins being introduced was to stop the illegal practice of 'clipping'.
Clipping involved cutting small slivers from the edges of coins. 
Once a sizeable hoard of clippings had been collected they were either melted down and turned in to new handmade coins or since this offence was punishable by death, sometimes sold to silversmiths.

In the photo below it is clear to see from the flat edges on the coin that it has been 'clipped'.

Edward irish halfpenny

Edward half groat

George I halfpenny 1723

George II half penny