The $1 bill most commonly comes from the United States currency system. It has several nicknames such as "buck," "single," "one," or "Washington" (because of George Washington's portrait featured on the bill). The term "buck" originated from a historical use of deerskins (bucks) as currency before paper money existed. People use these nicknames in everyday transactions, especially in retail and casual conversation, to refer to one US dollar.
If the question was about where a literal $1 came from in a situation (such as a math or riddle scenario), let me know if that context is needed for a more specific answer.
