A miser. A miser is a rich person that collects gold and stuff. Money boxes are made of gold so a miser.
Yuan.
Curency collecting is the field of Notaphily which refers specifically to the collecting of "bank notes" or currency as we call it. Sometimes collectors in this field are also called "rag pickers"...
Fiat money. This is money that has no tangible value. An alternative is gold, which in itself has tangible value.
Greenbacks