Marrowfat peas are green peas that have been allowed to mature and dry out naturally in the field. Marrowfat peas are starchy and are used to make mushy peas as well as in snack foods. They are used to make mushy peas and also the snack food wasabi peas. They are a traditional northern English accompaniment to fish and chips. All over Northern England they are commonly served as part of the popular snack of pie and peas.