Hi Tim,
Not sure if you checked out the other reply in this thread so letting you know what an expert said.
Steve gave this reply on another forum where I posted pics of the coin:
My friend and treasure hunting buddy of many years is Dr. Sewall Menzel. He's probably the world's foremost expert on cob coinage so I e-mailed him pics of your coin and asked him for his expert opinion. Here's what he wrote back:
"The coin is a 1721 M (Melgarejo assayer's initial), Lima mint. The date, assayer initial and denomination are all there. Good find......Lima mint mark (L) on the coin".
He also said the size of the coin suggests it is a one reale. Just thought you would like to know.