I can't remember the name of the song this came from but it's irrelevant because what I was wondering was, are the chestnuts that are roasting on the fire what we would call conkers? Also has anyone ever actually done this, as in roasted and eaten them, which I assume is what is happening in the song?
Horse chestnut trees produce conkers and they are poisonous.
Sweet chestnut trees produce chestnuts and they are delicious, especially roasted on an open fire at Christmas.