Heritage Auctions raked in $869,500 for two pennies—among the first examples struck by the US Mint in 1792—at its five-day auction of rare coins and paper money held this week in Anaheim, California.

The two coins, sold on Wednesday, August 10, account for nearly a tenth of the expected $10 million total sales for the auction house this week.

The winning bid of $352,500 was submitted for a 1792 Silver Center Cen, so-called for a small silver plug that was added so that its intrinsic value equaled its face value. The idea was suggested by Thomas Paine and endorsed by Thomas Jefferson in a letter to George Washington, according to the auction house. The copper penny is roughly the size of a modern US quarter.

The second penny was a 1792 Birch Cent. This was allegedly engraved by Robert Birch, who was one of the first engravers at the US Mint, though this remains unconfirmed. The coin is said to be the better of two known surviving examples of this experimental design, and sold for $517,000.

“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 Heritage Auctions president Greg Rohan.

The most expensive penny ever sold is also a 1792 Birch Cent, which a Los Angeles-based collector bought for $2,585,000 at Heritage Auctions in 2015. “They are literally Mona Lisas of our coinage,” the collector told the LA Times.

Heritage specialist Eric Bradley told artnet News that the $2.5 million Birch Cent was the best uncirculated example known, hence the hefty price at auction. “The current example was circulated,” he says.