There are many organizations involved in the Mardi Gras parades and they are called Krewes.
This Krewe having the name Cleopatra, which was founded in 1972 and is still active. It is an all female Krewe.
Each Krewe have their own theme and "throws" they toss to the people on the sidewalks as they parade a certain route in the City of New Orleans. The Krewes are scheduled to parade yearly on a certain date.
A Throw can be beads and/or Doubloons and sometimes other trinkets. The common doubloons are generally silver colored aluminum but there are different colored aluminum anodized medals too with a new design each year.
There are special ones minted for members of the Krewes or and special associates. Some in heavier medals, bronze, nickel or sometimes silver. These are much more scarce than a common aluminum "throw" but can be of the same design for that year.
This one is a special doubloon for the Cleopatra Coronation Ball. A celebration seperate from the parade.

This year the Krewe of Cleopatra will begin their parade the last day before Mardi Gras on Monday March 4 at 6:30 PM. Mardi Gras, or "Fat Tuesday," is the last day of the Carnival season as it always falls the day before Ash Wednesday, the first day of Lent.

I have several odd and more elusive Doubloons and my eye on a few others. Some are quite eye catching and a bit scarce with interesting quality artwork, while others or rather ordinary in my opinion. I thought this one was exceptional.