It was disk shaped and brilliant white on the bottom, flew at a high rate of speed and changed direction at 90 degree turns.

The crafts were aprox.100 foot in diameter. They flew about 150 foot above the ground,and I could here a high pitch whirring sound . 
I was riding a motor cycle and they came in from the east to the west, and paced me at about 50 Mph. I was startled and trying to reach home to tell some one about them.  
As I reached my destination, they accelerated  dramatically and changed direction at 90 degrees instantly, shooting up and out of sight. 
Rather than be ridiculed I did not press what I had witnessed.  
About a year after that, my own father that I thought wouldn't believe me, said the early one morning while doing farm work, witnessed one taking off from a valley on our other farm.  He kept his silence about this as well.  The craft was the same as I had witnessed aprox 100 foot in dia. and the bottoms were so bright that it was almost imposible to keep your eyes open.