Amazon.com has a huge selection of poetry books (many of which are very inexpensive) so I definitely recommend going there and looking for exactly what you want because you will probably find it there.
If you’re looking for some suggestions, here are a couple of the poetry books I’ve bought:
This 752 page book includes over 575 poems from all time periods (from ancient to contemporary) and from all over the world. Includes footnotes which explain the meanings of any unusual words.
I bought this book for $1.50, it’s hard to beat that. And yes it’s still available for that ridiculously low price (at least as I type this.) Includes poems by Edgar Allan Poe, Walt Whitman, Emily Dickenson, T.S. Eliot, Langston Hughes, and many more great American poets.
Kindle Wireless Reading Device
One of the very cool things about purchasing a Kindle is that it includes free access to over 1.8 million out of copyright books published before 1923. As you can imagine this includes a huge amount of free poetry (and obviously a ridiculous amount of great classic literature.)