Sounds like it might be the notorious brake caliper spring/clips. If your brakes have ever been serviced, there's a possibility that these might not have been reinstalled properly. I had this issue after I upgraded my brakes to the Toyota Supra Big Brake Kit. My tech installed everything properly but didn't put the springs in correctly. I would get a metal on metal clank on every bump from the wheel vertical movement and the pads moving. Search on this form, you will probably find my thread on this issue. Finally got fed up and took it to Lexus and they installed them correctly, after I was convinced that it was a suspension problem. I was wrong and the Lexus tech found the problem. Fixed the springs and greased the pads, all's good now.

 

Thanks, ShawnOK. I booked an appointment with Lexus and will have them check it out.