Hi Jack. The largest one I know of is at Wolf Lake which is about 20 miles south of Michigan in the eastern part of the state. I don't know the dates however.
They have them at Portland Ind also. Thats up by the Limberlost near Berne.
The grandaddy of all country auctions it up at Topeka Ind. One of the larger Amish groups in the US of Hay. They have A draft horse and machinery sale with over 1000 head of work horses, and about 5 acres of antique farm tools. 4 day sale. This spring is March 20 21 22 23. Fall sale is Oct 30 31 Nov 1 2.
They also have 3 carriage auctions each year. Over 300 buggys, carriages, sleighs, covered wagons, hitch wagons, hearses, and new harness, used harness, saddles, more antiques that are horse and farm related than you can have time to look at.
includes about 100 head of driving horses on the final day.
The dates for these sales are -- April 12 & 13.
June 14 & 15. Sept 27 & 28.
auction@topekanet.com