Eth (ð)
The y in ye actually comes from the letter eth, which slowly merged with y over time. In its purest form, eth was pronounced like the th sound in words like this, that or the. Linguistically, ye is meant to sound the same as the but the incorrect spelling and rampant mispronunciation live on.
https://omgfacts.com/we-used-to-have-6-more-letters-in-our-alphabet-a7e1a165853d#.a0pwtcyq5
