Not sure about veggies, but there are some herbs that are good year round. Thyme is one, and there are many varieties available, including mat-forming creeping types that can be used between stepping stones or in a rock garden. Rosemary is another wonderful herb, and is found in an upright form, and a low growing variety: Rosemarinus prostratus. Lavender is lovely in the winter, with the soft, silvery-gray leaves, and also has many varieties, including dwarf forms. Corsican mint is nice, if you have a shady spot for it. All of these herbs can be used in cooking.