Several 'new' charters (or improved texts of charters known hitherto from inferior transcripts) have come to light since the publication of Sawyer's catalogue in 1968. For texts derived ultimately from the archives of Abbotsbury, Athelney, Barking, London (St Paul's), St Albans, Westminster, and elsewhere, follow the links in the side menu.
In other cases, 'new' texts (in Latin and in the vernacular) have been discovered in the form of early modern transcripts of manuscripts now lost: transcripts made from charters formerly extant in their original single-sheet form, from the archives of Westminster and elsewhere; and notes made in the seventeenth century from a cartulary of Abbotsbury abbey (Dorset), from a cartulary of St Paul's cathedral (London), and from a cartulary of St Albans abbey (Hertfordshire).
There can be no doubt whatsoever that other texts are awaiting discovery and identification, most likely in the form of transcripts derived from one or other of several 'lost' cartularies (e.g. Buckfast, Burton, Glastonbury, Milton), or from single sheets (e.g. the missing transcripts of the Somers charters from Worcester); and it is by no means impossible that some 'original' charters are still to be found lurking in the cupboards or bottom drawers of England's country houses.
See, in general, Simon Keynes, 'Anglo-Saxon Charters: Lost and Found', Myth, Rulership, Church and Charters: Essays in Honour of Nicholas Brooks, ed. J. Barrow and A. Wareham (Aldershot, 2008), pp. 45-66.