A woman in England recently made a historical find in her own backyard.  Here’s the kicker, it may be worth up to $20,000!

Over the course of 10 years, the woman used what she believed was an old rock as a stepping stone to mount her horses.

One day, she noticed a wreath carved into the rock.  She decided to take it to an archeologist, who confirmed the old rock was in fact an ancient marble artifact worth up to $20,000, according to People Magazine.

The marble slab was discovered about 20 years ago in the southern England village of Whiteparish and is currently being sold at Woolley and Wallis auction house.  The archeologist determined that the rock likely dates back to 2nd century AD, with possible origins from Greece or Asia Minor.

The specialist from Woolley and Wallis Auction House noted that it is a “complete mystery” how the slab ended up in the woman’s backyard in the United Kingdom, but he hopes the public may be able to shed some light.

He added, “Both Cowesfield House and Broxmore House were very close to Whiteparish and were demolished in 1949 after having been requisitioned by the army during the war.”

“But we also know that the house at what is now Paulton’s Park was destroyed by fire in 1963 and so possibly rubble from there was reused at building sites in the area shortly afterwards,” he added.

It currently holds a pre-sale estimate value of £10,000-15,000 ($13,564-$20,346) USD.

Per CNN, the slab inscription reportedly reads: “The people [and] the Young Men [honor] Demetrios [son] of Metrodoros [the son] of Leukios.”