There are pockets of clay all over the Touraine and Berry and in the old days (i.e. the 19th century) there were tile and brick factories associated with almost every town and village. They are virtually all gone now, with a rare survival being the tile factory near le Blanc where we got our carreaux de terres cuites for the kitchen and entry hall.
with their stamps sharp and legible...
is not much better than at our house though.