The Old English digraph <eo> is often rendered in present-day English as a double <e>:
And many, many more.
If you dig this kind of stuff, you may want to sign up for the Old English for Orthographers LEXinar, five Mondays from 6:30-8:00pm Central Daylight time, June 23rd ~ July 21st.
Note: This inaugural Old English LEXinar is now full. Other schedules will be offered; or, gather your own group of three and propose a schedule to me!