Large Round Aircraft seen in Federal Way, Washington Approximately 1976

I am now 43 and I was 11 at the time this happened.  I will never forget the event and wish to this day I could draw because I can remember it like it was yesturday.
My parents and I were sitting in our living room in Federal Way, Washington on Star Lake Road.  We had a house that had two huge windows.  When out of the blue a very large round object appeared right in front of our windows.  It was about the size of 1/2 of football field.  There were rectangular lights that flashed in a circular motion.  There were to windshields that were the same size as the lights.  It was grey in color and made no noise what so ever.  My dad said"  Must be some new boeing project"  It just sat there for at least a minute.  My mom said ya right, I have never seen anything that that.  In a instant it shot straight up into the air and took off heading South towards Portland.  We called my aunt and she was like, I see nothing.  The strangest thing of all is the next day at breakfast my parents remembered seeing something but they both said it was a dream.  THen said, how can we all have the same dream.  I try now to talk to my parents about it, my mom is eager to tell it but my dad is dead silent and wont say a word.  I wish I could see it again.
Source of report indicates that the date of the incident is approximate.  PD