Saucer with red, green and white flashing lights over our horse pasture.

I was 10 years old when my mom called me out on the porch and asked me if i see what she is seeing.  She was calling really loud.
There was a saucer shaped craft hovering over the back side of our horse pasture 100 yards from our porch and about 20 feet off of the ground.  The horses ran back to the side of the pasture that the house was on.
It had red green and white flashing lights around the middle edge.  You could clearly make out the saucer shape.
It sat there about 10 minutes then slowly lifted straight up over the tree tops and flew away but not at a high rate of speed.  We could only hear a faint humming sound.
I know it has been a long time since I saw this when I was a child but I will never forget it. 
My mom never wanted to say anything or let me because she thought people back then would think she was crazy.
Date indicated for the incident probably is approximate, although the source of the report does not indicate that fact.  PD