At this moment, no one knows what these items are for. All I know is that they provide a little bit of orange light. My suggestion would be for maybe making a snowman? Maybe they are just decoration? I know that you cannot sell them to any NPC that we're aware of. It seems to be a good idea to keep coal eyes and the glowing carrot for down the road. Maybe something is already or will be implemented. I wish I could give you a better answer than this but this is just from what I know at the moment.