bonfire

The word bonfire originates from the expression bone fire - in olden days a fire for burning exclusively animal bones - but now applies to outdoor fires of wood and other waste plant material.  

Bonfires can also be lit in commemoration of of political, religious or other special events, e.g.: the German Walpurgisnacht or the UK's Guy Fawkes Night on every November 5th in celebration of the foiling in 1605 of a Roman Catholic plot to blow up the House of Lords.

There are few countryside smells more delightful than that of a good bonfire.  (The sweet smell of silage comes a close second - for me, anyway.  Probably not to everyone's taste.)