Lady's Bedstraw is found in waste ground and near the coast. The reddish roots are used for dyeing; family is Madder (Rubiaceae) a well known red dye. The plant I found is growing along the Tarka Trail cycle path (ex rail track) opposite the small town of Bideford, N. Devon. Not easy to pull out the roots, and many were left for next year's growth. This seemed a particularly large and well established plant. Bedstraw has many herbal uses.
Roots taken from plant ground need soaking for several days to soften, before boiling up. The red dye appears while soaking, and would probably dye without even boiling up.
Boiling roots of plant produces a red dye, the longer soaked the deeper red. Photos show the dye was absorbed onto the pan sides, which loses dye power available, so pan must be aluminium. Predicted colour is scarlet, so use stainless steel.
[Note: Post restructuring: Additional dye process images to be resized]