Hi Jennifer.  Your request turned up on a weaving bulleton board at American
Online and I hope the following information is of use to you.  I looked up
ingrain carpeting in a 1988 reference by Helene Von Rosenstiel and Gail
Caskey Winkler called "Floor Coverings for Historic Buildings: a Guide to
Selecting Reproductions" (The Presevation Press, National Trust for Historic
Preservation, 1785 Massachusetts Avenue, N.W., Washington, D.C. 20036).
According to these authors (p. 270), ingrain carpet is "An American term for
a flatwoven, reversible, wool carpet resembling a coverlet in which the
colors of the design on one side reverse on the other.  Also known as
English, Kidderminster, Scotch, double cloth and three-play and two-play
carpeting."  The volume includes various black and white photos of both
historic and reproduction examples.  Their appendix lists several
manufacturers of Ingrain carpets:
(1)  Family Heir-Loom Weavers, R.F.D. 3, Box 59E, Red Lion, PA 17356 (717)
246-2431 Just Ingrain.
(2) Scalamandre, 950 Third Avenue, New York, NY 10022 (212) 980-3888.  Range
of carpets.
(3) Sunflower Studio, Constance La Lena, 2851 Road B 1/2, Grand Junction, CO
81501 (303) 242-3883.  Range of rugs.
Please do acknowledge receipt of this communication.