Readers letters to the editor often spark stories. Journalists rounds, or beats, are only of the major news sources. They phone police, and fire departments. Too hot, too cold, tornadoes, floods. Come up with a new angle on a weather story and you've got a winner.
Most stories come from people contacting journalists, either face to face, on paper, or by phone.
Come up with a local angle on national news, or a new angle on a weather story or any other of the regular story types, and tell a journalist about it. This is a generalisation. Some books have sold extremely well without achieving any publicity except word of mouth - but I can't, for the life of me, remember any of their titles. Because, unless you spend a fortune in advertising, very few people will know your book exists. Whenever you're mentioned in the media it's free publicity.