Where do you find clay and what do you do with it?

We sourced most of our clay from a friends farm, where piles of it lay around from being dug up from a damn.  We did two car trips and filled the boot each time.  You can look around your local area, building sites, back roads.   White clay or grey clay is good.   If you do use natural clay like this you will need to soak it for a few weeks (2 or 3), prior to using it so it softens to a point you can stomp on it during the cob making.  Otherwise it’s like stepping on rocks.   You can buy powdered clay as well – which we used once in an emergency.  Which is so fine, it just needs a bit of water added to it and you are ready to go.