After briefly introducing my staff to Pete and Melvyn's work, a teacher asked me about the word "can." We technically could spell it differently, as we have another letter that represents the /k/ phoneme. So I did some research and thinking about the word.
Can, the auxiliary verb, is a function word and the origins are listed as the following:
Origin: before 900; ME,OE, pres. ind. sing. 1st, 3rd person of cunnan to know, know how; c. G, ON Goth kann; see ken, know
Can, the content word or the noun or verb having to do with containers has the following origin:
Origin: bef. 1000; ME, OE canne, c.G Kanne, ON kanna, all perh. WGmc; cf. LL canna small vessel
Both words have roots with the <k> spelling, so it would make sense that we could spell one with a <k> to differenciate the meanings.