In Islam, bread represents prosperity, and the ability to feed yourself and your family. This means humble baked goods take on a certain significance, and should never be thrown away. Although this is quite an old fashioned view these days, a good many Turks still can’t bear to throw old bread out, and instead leave it outside, hanging in a prominent place, for others to find. As far as superstitions go, this is a good one, especially when your neighbours might be going hungry.
Similarly, you should never step on a piece of bread in Turkey - pick it up and say “Bismillah” - “in the name of God”.