Small Change
Before embarking on a trip overseas, it is likely that you would change some currency of the country you are visiting at your bank or money changer. Having a credit card is handy but you would definitely need cash for a roadside burger or bus fare.
It is fine if you come home with unused foreign currency notes as these could always be sold back to your local friendly money changer at a slight loss as it is always buy high and sell low consideration. However, money changers do not accept coins and I have a big heap of foreign coins in various denominations kept in containers and coin boxes. I have recently transferred these coins into the Japanese Prosperity cat coin banks that were given to me by friends. I have roughly counted them and they are worth at least three hundred dollars.
On a holiday to Japan, I made sure I spent all the remaining Japanese currency at the airport while waiting to catch my flight home.
In future, I will have to remember to carry some of the loose change that I have when I travel but coins can be so heavy.
I bet they called it, prosper cat.