List of Old English Words in the OED/K

Old English	sb	English
K	.	In Old English, K is merely a supplemental symbol occasionally used instead of C for the guttural sound. But after the Conquest, in accordance with Norman usage, C was retained for the guttural only before a o u l r and K was substituted for the same sound before e i y and (later) n. hence now, in native words initial K now appears only before e i y and before n (:-OE. cn-), where it is no longer pronounced in standard English.