Sometimes you can even find money in the trash. guaka (talk) randomly came across a pile of 1 and 2 cent pieces next to some glass containers, in August 2014 in Brussels.
Some people use coins to open trash cans.
In Spain you can find coins in telephone booths and even make living with this. Of course you can find coins from telephone booths everywhere where they use coins for calling (Germany, Spain, Portugal etc), but in Spain it's somehow easier.
See also: making money.
On Moneyless.org you can find a lot of information about living without or with much less money, there's also an article about how to make money dumpster diving