When I mentioned the French equivalent - pois cassés - I obviously had in mind what you would prepare at home, though nowadays often it's bought as a bag of dried and powdered peas (with no additives). The word 'pottage' comes from the French word 'potage', which unsurprisingly meant a big pot and subsequently its contents - this was put on a sort of kitchen range called un potager built of stone or brick to cook slowly. The traditional ingredients were the vegetables and plants that were grown in a kitchen garden - which also came to be known as un potager.