Oh, Lordy...well, here are some, but there are about 23.5456 x 10^24 others.

Queen Elinor's Confession
Down in the valley
Red River valley
Wreck of old '97
Casey Jones and the variants (and esp. the variant that starts "Casey Jones was a son of a bitch....")
Roll me over in the clover
Green grow the lilacs
McDonald on the heights
Mary Ellen Carter
John Birch Society
Springhill mine disaster
Crabs walk sidewise
Sweet Survivor
There but for fortune
Outside of small circle of friends
I got a letter from LBJ
Draft dodger rag
Darcy Farrow
Outlawed Rapparee
Brennan on the moor
How can I keep from singing
Silent Night
Yankee Doodle
Roll, Alamaba, Roll
Mary L. Mackay
Willie McBride
And the band played waltzing Matilda
South Side Irish

...and a lot that have been mentioned above.

Ever notice how these sorts of songs seen ever fresh, which most rock music fades?