I regret that I don't know many of the songs you mention. Ah yes, the DT would be a good place to start. Now, let's see...

Yellow on the broom - looks interesting, but no tune is listed.

Bonny Keel Laddie - no trace, maybe I need more info.

Castle of Dromore - surely there must be a tune, but alas no.

Flowers of Edin* - No sign of it at all, maybe it's some cunning Scots spelling of flo'ers.

Midnight on the Water - Nope.

Ashokan Farewell - I knew this tune was missing and have it on my list to do.

Blackberry Blossom - Not a clue to words or tune.

I didn't dare check Mr Greenhaus' submissions, I have no doubt they would be correct in every respect.

I remain sir, your humble and obedient servant John