Blackberries are a great free source of pudding, are commonly found throughout the UK and can be harvested in sufficient numbers to have enough for a tasty crumble or pie within a fairly short space of time. Why not get out and about and collect some this weekend. This food is growing wild, so as long as you don't drive a 4X4 or sportscar to go and pick them, using this food resource should save carbon emissions and money too.