A Maya Angelou stamp that will be issued Tuesday features a quote attributed to her. But children’s book author named Joan Walsh Anglund says she wrote it first. (U.S. Postal Service)

A number of luminaries are expected at Tuesday morning’s unveiling ceremony for the new stamp honoring the late author Maya Angelou, among them first lady Michelle Obama. An 89-year-old children’s book author named Joan Walsh Anglund won’t be there. But her words will be: The quote on the stamp originated with Anglund.

“A bird doesn’t sing because it has an answer, it sings because it has a song,” the Angelou “Forever” stamp reads.

“Yes, that’s my quote,” Anglund said Monday night from her Connecticut home. It appears on page 15 of her book of poems “A Cup of Sun,” published in 1967. Only the pronouns and punctuation are changed, from “he” in Anglund’s original to “it” on the stamp.

A Postal Service spokesman, Mark Saunders, initially said he had never heard of the Anglund quote until The Washington Post informed him of it. In response, he sent a link to a 2013 blog post interview that quoted Angelou saying the phrase. In a later statement, he also said “numerous references” attributed the the quote to her as well.

“The Postal Service used her widely recognized quote to help build an immediate connection between her image and her 1969 nationally recognized autobiography, ‘I Know Why the Caged Bird Sings,’ ” the statement said.

The U.S. Postal Service unveiled a limited edition stamp honoring poet and civil rights activist Maya Angelou at the Warner Theatre in Washington, D.C. The first lady Michelle Obama, Oprah Winfrey and Attorney General Eric Holder were amongst those in attendance. (Reuters)

But Monday night, after being told that Anglund confirmed the quote as hers, Saunders wrote in an e-mail, “Had we known about this issue beforehand, we would have used one of [Angelou’s] many other works. . . . The sentence held great meaning for her and she is publicly identified with its popularity.”

Emily Anglund, Anglund’s granddaughter, said she had no idea that the quote has been attributed to Angelou for several years, or that it is featured on her forever stamp. “We didn’t realize it until you brought it to our attention now. Wow,” Emily Anglund said.

Last year, in remarks at the presentation of the 2013 National Medal of Arts and National Humanities Medal, President Obama attributed the quote to Angelou:

“The late, great Maya Angelou once said, ‘A bird doesn’t sing because it has an answer, it sings because it has a song.’ Each of the men and women that we honor today has a song — literally, in some cases. For others, it’s a talent, or a drive, or a passion that they just had to share with the world.”

Joan Walsh Anglund also was hearing about the Angelou stamp for the first time Monday night. “I haven’t read all of her things, and I love her things, of course,” she said of the poet and cultural icon. “But I think it easily happens sometimes that people hear something, and it’s kind of going into your subconscious and you don’t realize it,” she said.

“It’s an interesting connection, and interesting it would happen and already be printed and on her stamp,” Anglund said. “I love her and all she’s done, and I also love my own private thinking that also comes to the public because it comes from what I’ve been thinking and how I’ve been feeling.

“I don’t know about the stamp and I hope that it’s successful,” she added.