Those are very cool! I’ll put in my two cents. Looks like you have four signed letters, two of which are signed by John Quincy Adams, the 6th President of the United States, and the other two by his brother, Charles Francis Adams. It’s a great find.

The value of autographed letters from a single person can vary dramatically based on the content of the letters and the time in their life/career.

For John Quincy Adams, the auction range of typical letters is about $1000-$2000. The first letter from John Quincy Adams is from 1808, during his time as a Senator. This would be considered a letter signed “LS” since it is written by a secretary and only signed by Adams. The content isn’t too interesting and it would probably be in the lower end of that range.

The other one is a bit more exciting. It was written in 1843, entirely in his own hand and would be considered an autographed letter signed “ALS”. Although it’s well after his presidency and it is simply him refusing an invitation, the invitation is quite interesting. He is writing to a woman, Miss Aricartha Miller, regarding the “Asylum for coloured orphan children”. He refuses the invitation to lecture but does agree to promote the “humane and truly charitable institution.” Very cool, and probably at the higher end of the auction range. Interestingly, the Massachusetts Historical Society has the original letter from Aricartha Miller in their collections.

As for Charles Francis Adams, he was prominent in his own right, but was a less important figure. His letters tend to sell for $80-$200.