In Mother 3
In Chapter 2
Money was brought to the people of Tazmily Village by a suspicious peddler, given to Butch in exchange for his pigs. Prior to the events of Chapter 4, no money was used on the Nowhere Islands. Butch, seeing it as valuable, hid it inside the town well so nobody would steal it, asking Duster to keep it a secret. Unfortunately, it was stolen at the end of Chapter 2. Duster is blamed for the robbery due to the fact that, to Butch's knowledge, he was the only one who knew where he had hid the money.
In Chapter 3
Salsa sees Fassad steal the money from Tazmily Village's town well.
From Chapter 4 onward
Money reappears in Chapter 4, where its name is officially dubbed "Dragon Power". The player can withdraw or deposit DP from Save Frogs from that point on. DP can then be received by defeating enemies like in the previous games. The money won from enemies will be added to the money saved with the Save Frogs. It is unknown where the name "Dragon Power" comes from, what it is made of, or what it looks like. The name may have come from the Dark Dragon.
"Since Fassad's arrival in Tazmily, this has been used instead of acorns. It's round and shiny, but unlike acorns, it cannot be found in the forest."