The poem is included in the old classic
One Hundred and One Famous Poems as "The Deacon's Masterpiece or 'The One-Hoss Shay'"...the poem was first published in 1858 and is by the elder Holmes (1809-1894), the father of the Supreme Court justice.
Google will turn up a lot of online copies of the poem, including:
www.bartleby.com/102/103html