I do not know, one usually gets mail from companies associated with companies you have done business with. Could someone have sent your name and address to them?
Open them up and see if there is a piece of paper that contains an ‘opt out’ option. If so, call the number on it immediately. If that is not there, you can either shred them all up, or consider taking them to the post office. I believe sending naked pictures through the mail is considered porn, and using the mail makes it a federal offense.

You must have signed up to something on line which was sexually orientated, your address and identity has been sold in a mailing list, so you get sexual promotional post from unscrupulous companies!
Far too common I am afraid!