Gschaar itemsThe $2 bill that Robert J. Gschaar always carried with him, as a keepsake of his marriage, his World Trade Center building security pass and his wedding ring, which his widow has donated to the National September 11 Memorial and Museum. (Photos: David W. Dunlap/The New York Times)

It was the $2 bill that told Myrta Gschaar what she did not really want to know with such certainty: that her husband had been killed at the World Trade Center on Sept. 11, 2001.

Long after the 9/11 attack, Mrs. Gschaar had no tangible evidence of the death of her husband, Robert J. Gschaar, who worked at the Aon insurance company. He simply disappeared after calling her Tuesday morning to say that there had been an accident in the north tower. He was safe in the south tower, he told her, and would call again once he reached the street. But no second call ever came.

Three of four years passed before the special trade center property recovery unit of the Police Department let her know it had some items she might want. Most were self-explanatory, like a damaged security pass.

But there was something else. Among the items was a wallet. One of the items inside was a $2 Federal Reserve note, serial No. E52521814A.

“The definitive proof that it was her husband was the discovery of the $2 bill,” said Jan Seidler Ramirez, the chief curator of the National September 11 Memorial and Museum at the World Trade Center.

Before the couple married in 1989, Ms. Ramirez explained, Mr. Gschaar presented two $2 bills. They symbolized many things: that this would be the second marriage for both of them, that they were two of a kind, that it would be a second chance for happiness. He gave one bill to her and kept one for himself.

Mrs. Gschaar always held on to hers. And then she got his back. “This is what she needed to accept his death,” Ms. Ramirez said.

There is obviously tremendous power in such artifacts. But much of the resonance derives from the stories behind them. That is why the museum has invited victims’ families to participate in a digital archive, the Voices of September 11th Living Memorial; a recorded interview produced by StoryCorps; and to consider donating “photographs, memorabilia, personal effects, and other materials that are testaments to the lives and experiences of your loved ones.” The invitation went out by e-mail on Thursday.

Alice M. Greenwald, the museum director, said, “The world doesn’t know these people the way their families know them.” Having such objects and such personal narratives, she said, will help the museum deliver the message that “terrorism affects people just like us.”

Mrs. Gschaar has moved to Ohio from Spring Valley, N.Y. Her generosity was nothing short of extraordinary. Not only did she give the museum her husband’s wallet, and both bills, but also his wedding ring.

Ms. Ramirez recalled her saying: “I don’t need it anymore. I’m eternally wed to him. I want it to be with the $2 bill.”