While many picture books and easy readers are available as downloadable audiobooks from BARD at https://nlsbard.loc.gov, not all those books are also available pre-loaded on a cartridge for TBBC to send out through the mail.
School Library Journal (a magazine for teachers and librarians at www.schoollibraryjournal.com) is holding a purely for fun "battle of the kids books."
Sixteen books are selected.
Mary Burkey is a teacher, librarian, and audiobook expert.
She writes about anything and everything audiobook connected at Audiobooker at the Booklist Online website, at http://audiobooker.booklistonline.com/
Mary just wrote a great article about free audiobooks, including NLS books.