I did a radio prog on this once. To the best of my recollection I used:
We plough the fields and scatter.
Come ye thankful people come
John Barleycorn
Harvest Home (the one with the "Drink boys drink" chorus)
Harvest Home Hornpipe (get a clog-dancer in if you can)

Pretty obvious choices really, and all the better for being well-known and well-loved.