A great winter product is the rutabaga aka the classic New England turnip. Sow in mid September and as soon as the first leaves appear thin to eight inches.
Watch the weather reports and just before the first frost place a good thick layer, about 12 inches, of mulch hay over the bed and moisten well. Some folks even place strips of black plactic over the hay layer. If you are in a good area for snow you will not need the plastic. If you get very cold weather and not a lot of snow go with intermittent strips of plastic.
Other veggies which can be grown this way are parsnips, radishes and some cold varieties of beets.
Then there are the crucifers like the various cabbages, Brussels sprouts, and broccoli which can be planted very early or planted and harvested late. They love the cold. Plant in the spring as soon as you can work the ground and plant late August to mid September for harvest from the time the snow flies and beyond.
Garlic must be planted in the fall and is a good thing. Love garlic!
Hope all this helps!