As this is a website aimed at people who like to read, I thought I would take post to recommend the Standard Ebooks website.
Standard Ebooks is a volunteer organization which takes public domain books and then carefully edits them to bring them up to professional quality, including good typography, careful copyediting, attractive covers and so on. See the full explanation at the website. The books are then made available free in a variety of formats.
If you download some of their books and want to read them on your phone, I can recommend ReadEra as an excellent ebook reading app. It's free.
I have ReadEra on my Android phone, and I've downloaded four Standard Ebooks to the phone so far.
Note that the site will become more useful every year because Congress has finally stopped extending and.S. copyrights, so that each year another batch of books from the 1920s enters the public domain. As a result, books such as The Great Gatsby by F. Scott Fitzgerald and The Sun Also Rises by Ernest Hemingway have entered the public domain, and have become available in Standard Ebooks editions.
I should also point out that Standard Ebooks has some titles which appear on Robert Anton Wilson's "Brain Books" essay as books that RAW wrote "I wish everyone would read." (The essay is reprinted in Beyond Chaos and Beyond. Standard Ebooks doesn't have Ulysses by James Joyce yet (it's in the works, but other Joyce titles are offered), but among the books RAW recommended, it does have Progress and Poverty by Henry George and many editions of work of Shakespeare, also Gulliver's Travels by Jonathan Swift. RAW also was a Lovecraft fan, and the site includes a Lovecraft anthology.
The R.A. Lafferty anthology offered by Standard Ebooks is quite good and has many of his best stories.