Lammas Festival is a harvest festival observed in the UK on the 1st of August. Every culture seems to have their own harvest festival with their own practices. This one seems to have its roots in paganism. As per the pagans, Lammas bread is made using the first crop of the season. It is made with buttermilk.
The pagans blessed the bread and then broke it into four pieces, as a way of giving back to the crop of the season.
Lughnasadh is the Irish Lammas.