Sounds like 'The Monument (lest we forget)'. It's on Rain on the Roof cd.

In the corner of a quiet field there's a monument today
Put up by the mine workers of the UMWA
To mark the spot where children had their lives taken away
And it's standing there in case we might forget.

CHORUS
Lest we forget in case we might forget
How the rich man and his police and his press
Got away with murder then, they get away with it yet
And it's standing there in case we might forget.

You may turn the pages of your history books in vain
The first thing men of power learn is never to take the blame
Just tell the people shameless lies, does nothing ever change?
And history's always written by the winners.

In today's newspapers the headlines change so fast
So much information in the memory doesn't last
But if we learn nothing from the lessons of the past
I'm afraid that we are destined to relive it.

It's about the Ludlow Massacre (Colorado, 1913). You'll get the rest of the story from Andy's excellent sleeve notes on the CD.

Lots more information on Andy's website