I think what you are describing are the pre-printed interfacings. There are several sources for them, but this is one page that has the interfacings – scroll down a little to see the panels that are grids with squares:
http://www.ericas.com/quilting/printedinterfacing.htm
And this is the page with the patterns and books:
http://www.ericas.com/quilting/scraptherapy.htm
Here is another source:
http://hummingbird-highway.com/patte...p-grid-2-pack/
Here is a description of how to use the interfacing:
The ScrapTherapy Small Scrap Grid makes sewing 2" scraps easy and accurate. Use the grid lines to arrange the scraps, then fuse the scraps to the light weight interfacing, then fold on the lines and sew the seam allowance.
Hope this helps!