Circle Pattern

I am trying to create a pattern on a 48" x 36" surface. I need to create a pattern of "randomly" assigned circles within a range of diameters, to a field of points. The result should be a circle pattern that appears totally "random" like pieces of sand or gravel.

When I use random I get multiple circles on the same points. I understand this is because of how random works, it will create multiples values within a list.

I also need to be able to make sure that the circles do not overlap each other when they are generated with the the "random" diameter and assigned to "random" point in the field. 

I was trying out Jitter. not sure how to use it here. 

Can anyone help? 

Many thanks.