The occasion was " A Fine Excess : A Three-Day Celebration of Poetry , " a conference headlined by three Pulitzer Prize winners : Mark Strand , a former poet laureate of the United States , who won the prize in 1999 ; W. D. Snodgrass , who won in 1960 for his first book of poetry ; and Richard Wilbur , another former poet laureate , who won the Pulitzer twice , in 1957 and 1989 .