A 1792 Birch cent, perhaps engraved by Robert Birch, sold for $517,000.

ANAHEIM, CALIFORNIA—Two early American pennies, among the first struck by the U.S. Mint in 1792, sold for a combined $869,500 on Wednesday, August 10, day one of a five-day auction of American coinage conducted by Heritage Auctions. Heritage said the coins were among the most historically important coins to come to auction in more than 20 years.

A 1792 silver center cent, so named for the small silver plug in the center, sold for $352,500.

“As the first coins produced inside the U.S. Mint in Philadelphia, these two coins played an important role in the development of the United States’ monetary system,” said Greg Rohan, president of Heritage Auctions. “Interest in these rarities extended well beyond the historical: Both are in excellent condition for their age and type.”

A winning bid of $352,500 claimed a 1792 silver center cent, so named for a small silver plug added to make its intrinsic value equal to its face value. The concept was suggested by American patriot Thomas Paine and endorsed by Thomas Jefferson in a letter to President George Washington. The copper penny is about the size of today’s modern quarter.

The second penny was a 1792 Birch cent, supposedly engraved by Robert Birch, but never confirmed. The coin is the finer of the two known surviving examples of this experimental design and sold for $517,000.

If two cents bring $869,500, what will the remainder of the five-day auction of rare coins and paper money bring? Stay tuned—Heritage Auctions expects to break the $10 million mark for the event.