There are now over 33,000 books in the United States considered in the public domain. That means they’re ours. The copyright has expired.
Those books are available in several places.
The largest project of ebooks is Project Guttenberg
and the audio editions are available, as they are recorded by volunteer readers at http://librivox.org/
If you are looking for Shakespeare, Sir Arthur Conan Doyle, Jane Austen, Thoreau, Emerson, etc., consider a download and it’s transferable, or side-loadable to your ereader (Nook or Kindle).
Book image is in the public domain — copyleft @