Many families have some treasures in the attic. Fred Frelinghuysen knew he had something, too, but he realized its significance only when the time came to let it go.

The Frelinghuysens are among New Jersey's oldest and most distinguished political families, with roots stretching to 1720 and a roster in public service that includes senators, congressmen, a vice presidential candidate and a secretary of state. Schools, streets, a township and even an arboretum are named after them.

There is also, until recently unknown to any but a few family members, a Frelinghuysen stamp collection. It is not your uncle Pete's schoolboy album replete with five-and-dime commemoratives, but a large and expertly curated holding, put together by Peter H. B. Frelinghuysen Jr., a former congressman who died last year at age 95, that includes rarities from the earliest days of American postal history.

Now Peter Frelinghuysen's five children, including Fred and his brother Rodney, who is serving his ninth term representing New Jersey's 11th Congressional district, are putting the collection under the hammer in a two-day auction that began Wednesday in Manhattan.

"It was a passion for him for many years," said Fred Frelinghuysen, 58, discussing the difficult decision to sell his father's stamps in order to settle his estate. "We were always aware of the collection. It was something we would bring out when we were on vacation or had time to relax."

Among the show-stoppers are stamps like the Inverted Jenny, the iconic first American airmail stamp of 1918, on which a little blue biplane, nicknamed Jenny, was printed upside-down by mistake. Just 100 of those exist, and every year a couple of them come up for auction someplace, typically selling for six figures.

Except for Frelinghuysen's. His specimen, to be offered Thursday, has been up for auction only once in the nearly 100 years since it was discovered. At that sale, in 1932, a certain Mrs. F. - young Peter's mother - bought it for her son, paying $2,750. The seller was Peter's second cousin, Joseph S. Frelinghuysen Sr., a former United States senator.

According to Scott Trepel, the head of Robert A. Siegel Auction Galleries, which is selling the collection, the Frelinghuysens hold the record for an Inverted Jenny stamp owned for the longest time by one family.

"The emergence of the Frelinghuysen collection answers many questions about the whereabouts of important philatelic rarities, which were known from old photographs, but had seemingly vanished," Mr. Trepel, wrote in the sale catalog. The book includes a wealth of historical information about the stamps' origins, much of it collected in one place for the first time.

Many of these provisional stamps are crudely designed and printed. They are also exceedingly rare, some surviving in only a handful of examples. The total for the 95 lots sold Wednesday was $2.96 million, including the 15 percent buyers' premium.

Many of the United States stamps from the collection being offered Thursday were also salted away for decades. Some items previously thought to be "probably unique," according to the catalog description, now turn out to have long-lost twins, including a block of four three-cent stamps from 1867 with a marginal imprint reading "National Bank Note Co. New York."

To read the complete article, see:A Stamp Collection With Rare Delights Leaves a Family's Holdings for Auction(www.nytimes.com/2012/03/29/nyregion/frelinghuysen-familys-rare
-stamp-collection-goes-to-auction.html)