I decided to write down what's she's singing on the Pentangle version seen on YouTube. I'll send the MIDI to joy for the DT. (I hope the DT is still taking MIDI's.)
Am Em G
The trees they do grow high, the leaves they do grow green
Em G Am
Many's is the time my true love I've seen
Em G (how about Bm?)
Many an hour I've watched him all alone
Em G Em
He's young, but he's daily growing.
Please note - I'm not saying these are the exact chords Pentangle used. They are chords one would expect from the notes of the tune. However, they are probably right. But don't be discouraged if you can't play complex chords. You can add your personal touch by refusing to bellow each verse, with the same swoops on the same notes, the way that singer does.
(The Mudcat owes me big time for listening to that over and over to get the timing.)
They are for an alto voice. The lowest note is the A below the staff.