The ornate oak overmantle, which has links to Royalty, is being sold by Whitchurch Auctions and is estimated to bring between £1.9 million and £5m.
Two years ago however, it was infested with woodworm and was to be binned, according to its current owner Andrew Potter, who lives in Stafford.
Andrew acquired the artefact from Seighford Hall, near Stafford, intending to make it into a headboard for a bed.
But he has since been told of its true worth and now it is attracting attention from prospective buyers around the world.
"I said it would make a fantastic headboard and I was given it along with a receipt," Andrew said.
"I took it home and left it in my garage. Then there was the lockdown.
"I kept it in the garage and the weather was so hot it dried it out and all the woodworm was gone."
Andrew said he was later contacted by a museum expert who said it could be worth millions of pounds.
The stunning carving, which depicts Queen Elizabeth I coat of arms and is almost 9ft by 5ft, is currently being stored safely in a vault.
"I still can't believe what's happening, it's overwhelming," said Andrew.
"I've got people ringing me from all over the world."
It was discovered that the overmantle had been gifted to paymaster general Richard Eld by Queen Elizabeth I for services rendered to the crown.
Seighford Hall near Stafford, which is now being transformed into a luxury hotel, is also said to have been given to Richard by the Queen as a reward for his services as paymaster to the Royal forces in Ulster.
Michael Jones, an auctioneer at Whitchurch Auctions, said: "It carries a £2 million reserve as a unique artefact of great historical interest, standing eight foot across and carved by the best Tudor craftsmen.
"The piece has aroused attention from around the world and has pre auction bids to go with bids we are expecting on the day.
"It's great for our auction. We do sell some expensive things but nothing like this.
"There's nothing else like it on the market and not another one in the world."
The auction will be held online on Monday morning.
Visit easyliveauction.com and search for Whitchurch Auctions for more details and to bid.
Seighford Hall was acquired by First Blue Group in July 2020 after being derelict for nearly two decades.
Seighford Hall Hotel & SPA aims to have private log cabins in addition to luxury bedrooms surrounding the walled garden at the 21-acre site.
The bar and restaurant will serve locally sourced produce as well as utilising organic herbs and vegetables grown in the hotel’s own kitchen garden.
The health club and spa will also offer membership packages to non-residents.
About 150 jobs will be created when the venue between Newport and Stafford reopens to the public next year, in time for the festive season.