Peas (Pisum sativum) Were grown in the Mediterranean/West Asia by 8000BC. They were likely brought to Britain by the Romans. Originally, peas were dried and carefully stored as a reliable protein-rich food available for the whole year.
The fashion for eating the sweet “baby” peas seems to have started in France in the 1600s. King Louis XIV loved them, so all the other nobles did as well. They were a luxury food, only for the rich, until the American Clarence Birdseye found a way of quick-freezing peas that preserved their flavour in 1824.
Some of us still like mushy peas and pea soup.