B. Black and Sons - Beautiful wool fabrics, including wool flannel.
Burnley and Trowbridge - Accurate 18th century fabrics, many of which have equivalents in the 17th century.
Dorr Mil Store - This site sells wool for rug hooking. Their "Door wools" are quite nice quality.
Dharma Trading - Their hemp canvas can be good, especially when on sale.
Fabric Store.Com - Reliable source of various weights of linen fabric. Their 5 oz. fabric, “IL019” is a good medium weight for shirts and smocks. Buy “bleached” for white linens, or “Natural” for linings and utility work.
Hemp Traders - Wide variety of hemp fabrics, both canvas and light weight. ORDER#: CS-C11-DRK 100% Hemp Linen – Weight: 11 oz. Width: 60″ Their stiffer varieties of hemp canvas can be good for stiffening the bodices of petticoats.
Renaissance Fabrics - wide selection. Very nice fabrics, although not all are appropriate for pilgrims.
William Booth Draper - Booth is a great source for worsted wool tapes. He also carries a good selection of wool cloth.