I didn't know about the pronunciation of "ȝ", and the examples in the article about the silent "gh" helps explain some modern German/English cognates: "daughter/Tochter", "thought/gedacht", etc.

The northern dialect of Middle English that the Pearl poet wrote in ("The Pearl", "Gwain and the Green Knight") makes use of this letter, much more so than Chaucer's more southern English. It's actually possible to read Chaucer with the help of some vocabulary tips -- the Pearl poet, at least in my experience, is way harder.