Festivals
If you go to a festival, hang on until the last day. When most people have gone, take a look at the mess that has been left behind, often people just leave their tents for no good reason, take it and whatever else they have left. Otherwise they are wasted at the landfill.
Even better go to the festival for free by working as steward or as a litter pickers, Litter pickers always find the best treats lying lost, forgotten and unwanted on the floor.