Here are some examples of citations in the OED of Old English where they use a standalone crossed thorn, Ꝥ: Þu aclænsast Ꝥ weofod and ʒehalʒast. Þær after com swulke mon-qualm Ꝥ lute hær ...
Is the word formulæ, written with an æ at the end, valid in English? I stumbled upon this apparently plural form of formula in the Wiktionary. I had no idea the letter æ could occur in English. Does ...