GUEST: These are my dad's baseball autographs. He collected most of 'em as a young boy. So he was 14, 15 years old, grew up near Yankee Stadium.

And so he hung out at the ballpark all the time.

APPRAISER: Mm-hmm.

GUEST: And he kind of waited around the corner to see guys that came out with wet hair. He knew that they had to be ball players. So he'd run up to 'em and say, you know, "You're my favorite, can I get your autograph?" And that's how he got a lot of 'em. And then he also wrote hundreds of letters. He had a one-cent postcard in there and they'd sign it and send it back to him. So he collected most of 'em between 1945 and 1948.

APPRAISER: Tell me about the Ty Cobb.

GUEST: He had no idea what Ty Cobb's address was, just that he lived in a certain city in Georgia. So he wrote on the front of the letter, you know, "To Ty Cobb, Georgia." And somehow it got to him, signed it and mailed it back to him.

APPRAISER: And then back to your father.

GUEST: Yup.

APPRAISER: How about the 1948 Brooklyn's team government postcard?

GUEST: You know this one, uh, what he said is that they were able to take it into the locker room and they just laid 'em out on the table...

APPRAISER: Mm-hmm.

GUEST: ...and the players would come by and sign it and then they mailed it back to him.

APPRAISER: That's a tricky one with the postcards and the team balls from that era, from the New York Yankees, from the Brooklyn Dodgers. The collectors and fans wouldn't have a chance to see them sign these. So there's always the element of a potential clubhouse signature. In your case, the good news is there's only one, perhaps two, clubhouse signatures, the one we know for sure being Pete Reiser, but with all the Hall of Famers on there are authentic. Tell me about the Lou Gehrig.

GUEST: He actually bought that one.

APPRAISER: Okay.

GUEST: He said he paid a dollar or $1.50.

APPRAISER: It's a good thing he only paid $1.50 for it, because this is a secretarial signature. It doesn't have any value. Tell me about the Babe Ruth cut signature.

GUEST: They were, I guess, opening up a bowling alley in Mount Vernon, New York, and Babe Ruth was there to throw out the first bowling ball. My dad said he threw out a gutter ball, and then he ran up to him, and again, you know, "You're my favorite player. Can I get your signature?" And that's how he got that one.

APPRAISER: Let's talk about the Jackie Robinson. In this case, he sends off a request by mail for an autograph of Jackie Robinson. And what came back is a secretarial, in fact.

GUEST: Bummer.

APPRAISER: So these are what we call "non-malicious, but non-authentic signatures." These are done by people who signed on behalf of the players because the players were either too busy or overwhelmed by autograph requests. The Ty Cobb, it is an authentic signature. That one at auction would sell for somewhere between $800 to $1,000.

GUEST: Mm-hmm.

APPRAISER: The 1948 Brooklyn Dodgers team-signed postcard with Roy Campanella, Pee Wee Reese, Jackie Robinson, all authentic...

GUEST: Mm-hmm.

APPRAISER: ...would sell at auction for somewhere around $1,000 to $1,200.

GUEST: Mm-hmm.

APPRAISER: And then last is the Babe Ruth, would sell at auction for $5,000 to $6,000.

GUEST: Wow.

APPRAISER: I had time to review the 261 items that you've brought here today. I'd put an auction estimate of $14,000 to $16,000.

GUEST: All right, very good.

APPRAISER: So the Lou Gehrig autograph, if it had been authentic, would be worth $2,000 to $3,000 today.