If you knew anything about public domain you wouldn’t have asked such a stupid question.
The photos of Melanias GQ photoshoot are all over the web. Search Google Images or Bing Images for Melania GQ and you will find them along with other photos of her. Just be careful to have the appropriate safety filters on otherwise you might get a lot very nasty stuff including pornographic photos including those that purport to be, but are not of her.
It is very easy to upload an image taken from anywhere on the web to sites like Photobucket or Imgur, Flicker, etc. and then use a Meme generator like http://memegenerator.net/ . We see numerous photo memes posted here and on various blogs and Facebook all the time.
There is however most certainly a legitimate question as to whether doing this violates copyright or is an abuse of fair use. I am aware for instance that linking to Getty copyrighted images not part of their free and fair use library is verboten here because Getty Images is very aggressive about protecting their copyrights.
I am not sure of GQs or the photographers standing since theyve not sued over the images being uploaded and posted and turned into various memes (including here as a positive).
The question of fair use when it comes to using photos for political speech is a tricky one as discussed here:
Section 107 includes four factors to be considered in determining whether or not a particular use is fair:
The purpose and character of the use.
(More likely to be fair if the use is noncommercial and transformative the original is, in effect, turned into a new work with a different purpose.)
The nature of the copyrighted work.
(More likely to be fair if the copied work is factual, as opposed to creative.)
The amount and substantiality of the portion used in relation to the copyrighted work as a whole.
(More likely to be fair if the amount taken is small or not central to the copied work, but sometimes copying the entire work is fair.)
The effect of the use upon the market or the potential market for the copyrighted work.
(More likely to be fair if the new work doesnt compete with the copied work in the marketplace. That is, the new work isnt a substitute for the original.)
Several photos of Melania from a Harpers Bazaar was posted on this thread. Did anyone here ask permission before posting them?
http://www.freerepublic.com/focus/news/3380607/posts
FWIW GQ doesnt seem to be putting up any objections and even seem to be loving all the free publicity:
http://www.gq-magazine.co.uk/article/donald-trump-melania-trump-knauss-first-lady-erections
http://www.gq-magazine.co.uk/article/donald-trump-melania-trump-gq-photo-shoot
But turning this picture also from GQ into a meme is OK I guess: