Every summer, booklovers and bargain hunters eagerly await the Friends of the Richard Byrd Library book sale, one of the largest in the region with more than 10,000 books, many in pristine condition.

While the sale always includes a diverse array of books, this sale includes something extra: books with a mysterious past.

“The mystery began in late December when a truck pulled up to the back of Richard Byrd Library to deliver more than 400 professionally packed books,” said Christine Peterson, president of the Friends of Richard Byrd Library.

“No one noticed any lettering on the truck to indicate where it came from. As the Friends of the Richard Byrd Library team unpacked, they realized they were looking at new, beautiful books,” Peterson said.

She said books from the mysterious donor include volumes on art, decorating, cooking, history and many other topics.

“While shoppers always find treasures at our sale, this time the treasures will be even more bountiful,” Peterson said, adding that she still does not know who delivered the books.

The sale begins Thursday, May 30, at 3 p.m. and runs through June 1 at the Richard Byrd Library, 7250 Commerce St. Proceeds benefit the library’s summer programs.

“Whether you want beautiful birthday, graduation and Father's Day book gifts on a budget or vacation and summer reading for the whole family, you will find something at our sale,” Peterson said. For more information, go to www.fairfaxcounty.gov/library/friends/rb/.