Thanks everyone for the quick replies!  I purchased some white on black woven fabric from Brookdale in NH.  Looks like Johnnys has it too.  Hoping that does the trick with blocking weeds and reflecting light.  I had one response that mentioned it.  Is anyone else out there using it?

-I've used it.  It did not block the sun enough to prevent weeds from growing.  Total disaster.

-I tried this in a high tunnel last season and it did not block weeds nearly as well as the black fabric.  Certainly the weeds were contained, but they survived under the fabric for the entire season - some even forming seed heads!  It did seem to help to a small degree with temperature and light reflection, but I don’t plan to use it again in this way. Maybe others have had better luck with it. 

-No Andrew, the white fabric is not nearly as effective at blocking weeds, ad is the black. So last year we bought a roll of white on black fabric and it worked perfectly.  We have ordered more white on black this year.  It breathes and lets water through just as well as the black alone, and provides 100% weed control.

-Weeds grow underneath in my experience

-Weeds grow like nuts under it!

-We have trialed the plain white woven fabric and it really does not block weeds. The Reflective White/Black Ground Cover is a much better choice because it is a good mix of reflecting light and suppressing weeds.