Thanks for these. Keep 'em coming.

On a three hour show I can probably fit in about 30 tracks. Whittling down to 30 could be fun.

Someone elsewhere has suggested Alice's Restaurant. That'll need a prog to itself! But it was iconic in it's time.

I'm particularly looking for tracks that stood out like milestones in the folk process, sending it in a new direction, or those that kick-started it.

Perhaps rather obvious, but
The Times they are a-changin' - Bob Dylan
The Sound of Silence - S & G
A Sailor's Life- Fairport
This Land is Your Land - Woody
Byker Hill - The Young Tradition