Potato wise I have several bags of potatoes in smaller size bags in my freezer. I parboil or bake batches at a time. Then dice up, some with skin on, in smaller portion bags. I shred up several potatoes and put into bags, and you can freeze mashed potatoes though I just prefer to freeze the boiled potatoes and then throw into a pot with some milk/butter.
As for cabbage, you can shred for eggrolls, stir fry, coleslaw(sweet or spicy), make kraut. We love to mix kraut with our mashed potatoes and serve with kielbasa. I think shredded cabbage is just a great filler in salads, pasta salad, stir fry, and anything else you can think of.