(Professional Sports Authenticator via AP)

A treasure trove of vintage Ty Cobb baseball cards, produced in the early 1900s as part of a set that collectors call “The Monster,” has been discovered in one of the oddest places imagineable — a beat-up paper bag inside the dilapidated house of a deceased great-grandfather.

Imagine the reaction of the family members, who wish to remain anonymous, when they opened the bag and found seven Cobb cards. They called Rick Snyder of MINT State Inc., in Myrtle Beach, S.C., and he was initially dubious.

“I doubted they were authentic because finding seven of these cards at one place at one time seemed almost impossible,” Snyder told the Associated Press.

A week later, he looked at them and knew they were the real deal and, on Wednesday, experts in Southern California agreed that the cards were part of the epic T206 series printed from 1909 to 1911. Those turn up from time to time and, when they do, the world sits up and takes notice. A near-mint-condition T206 Honus Wagner — the “Holy Grail” of baseball cards — brought the highest price ever for a baseball card, $2.8 million, in 2007. Also known as the “Mona Lisa” of cards, it was printed in 1909 and was purchased by Ken Kendrick, owner of the Arizona Diamondbacks.

Last April, a Wagner card from the T206 series brought $1.32 million at auction. Only 50 to 60 of those are believed to exist and and less than 10 are in excellent condition. The condition of that card was rated a 3 on a 1-10 scale.

Orlando estimates the value of the Cobb cards at more than $1 million and says that their condition ranges from 3.5 to 4.5 on the 1-10 scale.

“I am not sure if any other baseball card find is more remarkable than this new discovery,” Joe Orlando, president of Professional Sports Authenticator in Newport Beach, Calif., said in a statement to the AP.

Before the discovery of the seven Cobb cards, only 15 were known to exist. On the back, “TY COBB — KING OF THE SMOKING TOBACCO WORLD” is printed in green ink.

“The T206 set is known as ‘The Monster’ among collectors. It’s just really tough to complete the entire set,” Chris Ivy, director of sports auctions at Heritage Auction Galleries, told the AP in 2010 when a Wagner card that was battered and laminated was left in a will to a group of nuns in Baltimore. He described that Wagner card as “one of those that’s always sought-after, always desirable, and there’s not a big population of them. Even in a lower grade, they do have quite a bit of demand and command a strong price.”

In 2010, that card, left to the nuns by the brother of a nun, brought $220,000 for School Sisters of Notre Dame ministries in 35 countries at auction.

The back of one of seven Ty Cobb baseball cards. (Professional Sports Authenticator via AP)

It is unclear what the family with the Cobb cards will do with them and what effect the arrival of more cards will do to the market, but Orlando believes one thing is certain.

“This is one of the greatest discoveries in the history of our hobby,” Orlando said.