One would expect wool and linen to be readily available in early medieval Britain, as the climate is suitable for growing flax and rearing sheep. What about exotic luxury textiles, like silk?
Textiles, like other organic materials, do not usually survive well in archaeological deposits, unless the environment is either very dry (e.g. caves in a desert) or waterlogged (e.g. peat bogs). However, if textiles are deposited in close contact with metal objects, the corrosion of the metal can sometimes preserve fragments of the associated textile, either directly or as an impression in the corrosion products.
One of the funerary practices in widespread use by the early English ('Anglo-Saxons'), before they converted to Christianity, was inhumation burial with grave goods. The body was placed in the grave fully clothed, complete with jewellery and clothing fasteners such as brooches and belt buckles. Many of the clothing fasteners were made of metal, commonly copper alloy (bronze and related materials) or iron. Other metal objects such as tools, weapons or personal possessions were sometimes also buried with the body, and where these items touched clothing or other textiles such as cloth bags or wrappers they may also preserve fragments of textile.
Obviously, these tiny pieces of preserved fabric say very little about the overall shape and structure of the garments or cloths they were once part of. Nevertheless, they can say a great deal about the types of fibres, the spinning and weaving techniques used, and even, with careful chemical analysis, about dyes, colours and patterns.
Analysis of 3,800 records of preserved textiles from 1,730 graves excavated in what is now England has provided a wealth of information (Walton Rogers 2007). It should be noted that, by definition, this is a sample of textiles buried in graves containing metal objects, and may not necessarily be representative of textiles in use that were not deposited as grave goods, or textiles that were deposited in graves that did not contain metal objects. This caveat aside, however, it probably gives us a reasonable idea (and very likely the best we are going to get) of the textiles in use in Anglo-Saxon England.
Two fragments of silk cloth have been recorded (Walton Rogers 2007):
The smith had a miscellaneous collection of goods from Continental Europe, perhaps acquired in extensive travels (Walton Rogers 2007).
...you have sent, namely, an all silk robe for the relics of Bede, our master of blessed memory...
--Letter of Cuthbert to Lul, quoted in Crossley-Holland 1999
Note: this Abbot Cuthbert is not the same as the famous St Cuthbert, who lived in the previous century.
Among other things, he brought two cloaks, all of silk, and of incomparable workmanship, for which he received an estate of three hides on the south bank of the river Were, near, its mouth, from King Alfrid
--Bede, Lives of the Abbots of Wearmouth and Jarrow, Chapter 9, available online
The abbot in question is Benedict Biscop. King Aldfrid became king of Northumbria in 684 (Bede, Ecclesiastical History, Book IV Ch.26). One hide was the area of land required to support one family.
For hare lip, pound mastic very small, add the white of an egg, and mingle as thou dost vermillion, cut
with a knife the false edges of the lip, sew fast with silk, then smear without and within with the salve,
ere the silk rot. If it draw together, arrange it with the hand ; anoint again soon.
--Leechbook of Bald, Book I chapter 13, translated by Cockayne, 1860, searchable online
If someone's bowels be out [ .] put the bowel back into the man, sew it together with silk
--Leechbook of Bald, Book III chapter 73, translated in Pollington 2000
The Leechbook was probably compiled in the late ninth or early tenth century. For more information, see the article on 'Early medieval surgical knowledge'.
The archaeological samples and the documentary evidence are consistent. Silk cloth was clearly known in Anglo-Saxon England in the sixth, seventh and eighth centuries. It was also clearly very rare, very expensive (two silk cloaks bought enough farmland to support three families), and confined to people who had contacts with Continental Europe (Benedict Biscop brought silk cloaks back from Rome; Abbot Cuthbert received a silk robe from the Archbishop of Mainz in what is now Germany; the grave in Dover contained a brooch from Merovingian France; the smith at Tattershall Thorpe had several items from Europe and had perhaps travelled widely). Silk thread was evidently known in the ninth-tenth century, when the Leechbook was compiled.
Bede, Ecclesiastical history of the English people. Translated by Leo Sherley-Price. Penguin Classics, 1968, ISBN 0-14-044565-X.
Bede, Lives of the Abbots of Wearmouth and Jarrow, Chapter 9, available online
Crossley-Holland K. The Anglo-Saxon world: an anthology. Oxford University Press 1999, ISBN 0-19-283547-5.
Pollington S. Leechcraft: Early English charms, plantlore and healing. Anglo-Saxon Books, 2000, ISBN 978-1-898281-23-8.
Walton Rogers P. Cloth and clothing in early Anglo-Saxon England. Council for British Archaeology 2007, ISBN 978-1-902771-54-0.
*In tabby weave the weft threads go alternately under and over one warp thread at a time; in twill weave the weft threads go over and under two or more warp threads at a time, each row stepping one thread to the side of the previous row. Tabby weaving is the simplest type, and if you did some hand-weaving in junior school it was almost certainly tabby weaving.