ZOMG I loves me some kittehs. Cute! You can tell who the brave one is already.
I published a book in 1998 that's in the Library of Congress. You make something (book, record, CD, map, print, film, etc), send it to the Library of Congress (get a LCCN # first, along with your ISBN / ISSN or whatever else you need), and poof: it's considered to be in the Library of Congress. They accept and catalog all of it, put much into storage, get rid of some of it, and put the remaining items out for public consumption. I went on a LoC kick a few years ago trying to figure out exactly what they did with all that stuff.
That said, I'd say it doesn't really matter if it's in the LoC - if it's original, it's a something.
(NB: if you wanna buy my book, I let it go out of print and it's a "collectible" now - here it is on Amazon) - I am not any of those sellers and no idea why the book is fetching those prices. I have a stash and am letting them ferment a couple more decades.