The large bottles of dwarven ale are from Rimmer (he gives you 5 bottles when you bring him a message from his brother in the dwarven halls, or you can buy them through speech options, if he was alive). The mayor may accept other dwarven ale, but AFAIK the easter egg area requires those from Rimmer. I don't think the same type can be found randomly, but I'm not sure.
See this screenshot of the
eater egg items.
