Works published prior to 1923 would be in the public domain. The copyright claimant for newer works seems to be adopted son Lawrence Untermeyer.
If you have a copy of the poem in a book, there is likely better copyright information there; if not, a reasonable first move is to contact the publisher.
What is the value of longfellow's poems by Henry w. Longfellow
Google Books
I wouldn't think that would qualify as copyright infringement because aren't his poems under public domain?
No. Copyright is assigned to the Dr. Seuss Foundation, and administered by Audrey Geisel.
do i send poems to washington in finished book form or individually in a bulk package
The copyright to A.A. Milne's poems is owned by the Milne Estate. At the time of his death, the copyright passed to his widow and then to subsequent heirs. The exclusive rights to reproduce, distribute, and adapt the works are protected under copyright law.
The copyright holder of Octavio Paz's poems would be his estate or designated literary executor, typically a family member or organization tasked with managing his literary works and licensing their use.
Sonneteer can be used, I think. Also: Unemployed, liberal arts graduate, alcoholic... Any of those, really.
If the copyright was renewed, it would now belong to Random House (Doran -> Doubleday Doran -> Bantam Doubleday Dell -> Random House).
Copyright is a noun, or an adjective as in the phrase "copyright protection."
Just the one: copyright.
There are many places to find anniversary poems online. "PoemHunter" and "Family Friend Poems" are two websites that one can visit to find anniversary poems.