Scrooge McDuck has a lucky coin, which was the first coin he ever earned. Which coin is it?

Explanation

Scrooge McDuck is a stingy, old duck created by Carl Barks in 1947. He came from a poor, Scottish background and is now the richest duck in the world and lives in a money bin. His lucky coin is the first dime he ever earned. Scrooge McDuck is the son of Fergus McDuck and Downy O'Drake and he has two sisters: Matilda McDuck and Hortense McDuck.