In an interview with Goodreads.com, crime novelist Tana French offers a good example of how even very ordinary things feed into a book when that's on your mind. The book she's talking about is "Faithful Place" and the character is undercover cop Frank Mackey:
"In front of a house being gutted I saw a huge dumpster. Among all of these horrible broken lamps and rolls of ripped up, moldy wallpaper there was a battered old blue suitcase. I started thinking, "I wonder how that got there and how long it'd been in that old house and what's inside it?" That tied in with how I'd been thinking about Frank. What would be so crucially important to him that he would be backed into a corner? I thought the discovery of a suitcase [could reveal] that his first love, Rosie—who he thought had run away on him—may not have left him after all. Frank thought he had left home and family behind. Then he starts to be drawn back by this discovery."
To me this is a great demonstration of how important it is for writers to have time to wander, undistracted by phones, mp3 players, etc.--so there is space to be distracted by other things that can connect with and contribute to whatever you are working on.
(There are also ways you can coax inspiration to visit--for instructions, see my book, "Creativity Now!" published by Pearson and available from Amazon and other online and offline retailers.)