I have no idea what a "brake washer" would be. Does your car have 4 wheel disc brakes, or do you have drums in the rear? That noise sounds like a rust ridge on the inner or outer circumference of a brake rotor that is now turning in to part of the braking surface.
Take a look at your rotors inside and out to see if there is an area where the rust appears like it's starting to get polished. If so, replace the rotors or, if they still have enough thickness remaining, have them machined.
-Rod