Well little one, back in the time when your great-grandparents were young, the United States had lots of different pieces of paper called money. Some of these were worth more than others and people used them to buy things like food, clothing and toys.
Between the years 1922 and 1931, the United States government made a bunch of different versions of these pieces of paper called bills. They had pictures of important people like presidents and famous Americans on them. Some were worth more than others, just like today.
The regular issues of bills during this time period had different designs on each one, with special patterns and unique features. Some even had different colors, like green and blue! These special designs made it harder for people to copy the bills and make fake money.
People used these regular issue bills to buy things they needed or wanted, just like we do today when we use coins and bills to buy treats or toys. Overall, the regular issues of bills from 1922-1931 were just another type of money that people used to trade for things they wanted or needed in their daily lives.