David Owen in The New Yorker on the U.S. penny, which is worth less than it costs to produce:
A modern penny simply isn’t worth enough to worry about. In 1940, an average one-pound loaf of bread sold for eight cents, according to the U.S. Census Bureau. That means that a penny in those days bought enough bread to make a good-sized sandwich. These days, a penny doesn’t buy much more than a bit of crust. Accurately comparing monetary values (and bread loaves) across decades is impossible, but by almost any economic measure a 1940 penny had more purchasing power than a modern quarter does.
I’ve been throwing pennies away for years.