If you are looking for literature to incorporate into your STEM curriculum to inspire young inventors, the book Girls Think of Everything: Stories of Ingenious Inventions by Women by Catherine Thimmesh is a great resource. It is a collection of brief biographies of women and girls whose creative ideas changed the world. The last few entries feature young inventors, including ten year old Becky Schroder who was the youngest female to receive a U.S. patent when she invented Glo-sheet, paper that allows you to write in the dark. (Perhaps that will inspire writers as well as inventors!) The book also includes a list of organizations' postal and internet addresses that can help your students get started on the path to developing their own innovative ideas.
Once the ideas start flowing, encourage students to record them in their writer's notebook. If they are having difficulty thinking of of new ideas, have them read through their notebook and look for entries about things that "bug" them, or about situations that did not turn out the way they had hoped. Perhaps this will inspire them to rework an existing product or develop the idea for something that could improve the situation or eliminate frustration from those things that annoy them.