Lots of people say you can and my Mumused to. I remember cheese and pickle and luncheon meat. The memories of the cold luncheon meat is possibly what has stopped me doing it.
I do freeze smoked salmon in flat sandwich portions which makes quick work of a sandwich. (DS2 loves smoked salmon and I have a friend who brings him packets as a present instead of sweets, the other DC get strawberries.)
I'm pretty sure you can freeze any of those things, just don't add salad as it will go soggy when it defrost. I'd do this for upcoming new DC2 but as a vegetarian who loves my sandwiches stuffed with salad I don't think it's gonna work for me