Well, depending on where you are in northern Iowa, but, on the second weekend in Sept, there is the Fort Belmont rondy in Jackson, Mn, first weekend in Oct, there is Big Island in Albert Lea, Mn, and the forth weekend in July, you have the Love of the Land rondy in Pipestone Mn. There are more I know that can be found in the Powder Horn News, which is a monthly news letter listing almost all the rondys through out the country, as well as some good reading. For only $20 you can have a 1 year subscription, and it's published in your home state.
Powder Horn News
P.O. Box 86
Aurelia, Iowa 51005-0086