Honey Bee Hive prints patterns on three foundation cloths (also known as backing materials), they are in order of popularity:
Linen: 100% flax, 13 x 13 count , our recommended backing.  About 80% of our customers purchase this backing.  It can be used for both primitive and fine rug hooking. It often looks and feels like burlap, but it is a much stronger backing because the flax threads are longer than in traditional burlap.
Rug Warp: 100% cotton, 13 x 13 count, is a heavier backing. It can be used for both fine and primitive rug hooking. About 15% of our customers purchase this backing, especially for larger designs, as it is most cost effective than linen.
Monks Cloth: A popular cotton backing that is lightweight and soft.  It can has a double-thread weave, much like that of a cross-stitch pattern.  Therefore it has a 24 x 26 thread count.  It is not intended for footstool patterns, or other multi-dimensional projects as it has a tendency to stretch, so rug hookers have to be careful not to pack their loops too tightly when using this backing. Less than 5% of our customers order this backing.
We also offer these backings for sale, by the yard, and as custom sized and serged pieces.
Click here to see our collection of Foundation Cloth and Backing Materials, and purchase either by-the-yard or custom sized and serged pieces.