coin, coign, quoin

Coin or coin means a disk of metal of some kind, used as money--
 "May you purse always hold a coin or two..."
This machine doesn't accept bills; we'll have to look for a dollar coin.

Coin also means to make metal into money--
Only the government may coin money.
The U.S. Mint is where you can watch our government coin money.

Coin also means to invent a new word or phrase--
He was sure that he had coined a new phrase, but no one repeated it.
Texting inspired him to coin several new phrases, such as "R U home?"

Quoin or quoin ( rhymes with coin, sometimes spelled Coign or coign ) means the outside corner of a brick or stone building--
At a quoin of the building you will see a cornerstone, with the year of its construction carved on it."
The old man stood by a quoin of the wall, asking alms of passersby.

Quoin also means a wedge or corner-shaped brick or block--
The building is red brick, but each layer has a quoin made of a different material.
Printers still use a quoin to hold type securely in the tray.

Now that you know that, you can say--
"At a quoin of the old stone wall, the old man found a gold coin."