When Deborah Eisenberg answered the phone Tuesday and heard she had won the PEN/Faulkner Award for Fiction, she was sure she was stammering.

“I got a phone call, which is an amazing way to find out anything, to hear an actual human voice,” she said hours later, by phone, and described her reaction as “flabbergasted.”

Eisenberg, 65, has been writing since “I first picked up a pencil in 1975.” That first short piece is included in “The Collected Stories of Deborah Eisenberg,” a compilation of four volumes of her work, which the PEN/Faulkner judges selected as the best fiction from among 320 novels and short-story submissions.

In the years since her debut, Eisenberg has been saluted as one of the country’s best short-story writers. A PEN/Faulkner finalist in 2007, she has also received MacArthur and Guggenheim fellowships.

Creating these stories hasn’t been easy. “Writing is a struggle for me, and when I am unable to write, it is extremely painful,” Eisenberg said. She is just emerging from what she calls “a long arid period.”

“I started up again a year ago. I do think one exhausts one’s resources and obsessions for a while. At least that’s true for me. You can’t force your unconscious to render up something particularly fascinating or compelling to you, not to say to others,” Eisenberg said.

The prize, a $15,000 honorarium, is given at a dinner ceremony May 7 at the Folger Shakespeare Library, which administers the PEN/Faulkner program. In addition to Eisenberg, the finalists were Jennifer Egan, Jaimy Gordon, Eric Puchner and Brad Watson.