All books commercially published in the US in 1927 are now in the public domain! Books in the public domain are "owned" by everyone. Anyone has the right to read, share, or publish these works. When someone provides open access to a lesser known or out-of-print book in the public domain, that book is saved from potential obscurity. 

Duke's Center for the Study of Public Domain has a list of books that are entering public domain this year!