Investigate whether the poem qualified for a copyright. According to the U.S. Copyright Office, a collection of poems can be copyrighted if it is orderly and has a title, and each listed author (in an anthology) has contributed something to the book.
Check for a copyright mark. Some authors and publishers may choose to include a copyright mark, which is an encircled c, at the end of their poem or at the beginning of the book. To be valid, this copyright must be registered with the U.S. Copyright Office.
Look up information about the author. Authors hold the copyright on their work for 70 years after their death. However, if the poem was commissioned by an organization or another individual, the copyright holds for 95 years after the first publication of the book or 120 years after its creation, whichever comes first.
Search for the poem in the online database of the U.S. Copyright Office (see Resources). This easily accessible database provides information about the copyright status of poems. You can search using several criteria, including by author and by title.