Large disk, with lights running around it, floated very low and silently across a field near Lakeside Dr in Lisle, IL.

My mom and our neighbor were living in apartments outside of Chicago at the Four Lakes complex in Lisle, IL, on Lakeside Drive.  We were at his place watching the movie and were about to go home.
I can not be sure of the date, as it was so long ago, and I was quite young, maybe 6 or 7 years old.  What I can say for sure is that it was in the mid '70's (maybe '75) 'Gone With The Wind - Part 1" had just finished airing on television when we stepped outside after the movie.  It must have been around 10:30-11pm.  We stepped outside on a cold but clear night and looked at an open field to see a large saucer shape silently move from left to right across the field and over the trees across the course of maybe 10-20 seconds.  It was no more than a few hundred meters away, and appeared to be 30-50 feet across, roughly the same altitude as it measured across.  If you held your hand outstretched and away from your body, it was easily as wide as a large hand hand, if not bigger!  I do not recall any clear features on the top or bottom, however a row of lights or windows around around it's circumference. At the time I thought I could make out figures inside, however it could also have been diffused shadows between the lights, which were ran around the edge between the top/bottom sections. It was hard to tell, as the disc appeared to be slowly rotating.
It was a dark night, flying over a poorly lit field, so I can not say for sure if it was a sliver metallic finish, but that was definitely the impression I have always had. There was no wind, and it was completely silent  After it left our field of vision, we stared blankly at the empty field for a few moments before staring at each other without saying a word. We then exchanged looks and went inside.
In the weeks that followed I brought it up with my mom, and we both agreed it was strange, and definitely not something conventional like a helicopter or blimp.
While driving with my mom in about 2012 she asked if I remembered the 'UFO we saw'. I assumed she had forgotten about the experience, and I was beginning to wonder if I had imagined it, so it was a relief to hear her bring it up.
As I never forgot the experience, and had my own clear memory of it, I got her to tell me HER memories of the event before I said anything further, and they matched my recollection perfectly. I only had to remind her what movie we were watching.
I offer this in the hope that perhaps it might be 1 small report to help tell a much bigger story  note: The Good Year Blimp was active at the time, with blinking lights/signage. I witnessed it from the viewing deck of the Sears Tower only a few weeks later (at night), and it was definitely not the same.
Like many teenage boys I got heavily into aircraft after 'Top Gun' came out.  Friends used to test each other on aircraft identification, sometimes based on photos from just a small sections of the aircraft.  I have also had a passion for all things aerospace, and had been to several airshows as a kid and adult.  While that is a far cry from a 'trained observer,' I have never seen anything even closely resembling what we saw.
Witness indicates that the date of the event is approximate.  PD