Agricultural Fairs Rescue Act This bill directs the Agricultural Marketing Service of the Department of Agriculture to establish a program to award grants to state departments of agriculture to provide support to agricultural fairs for losses sustained by such fairs due to COVID-19 (i.e., coronavirus disease 2019). Grant amounts shall be based on the difference between the average attendance at agricultural fairs in the state for (1) a calendar year occurring during the three-year period beginning with 2017 or, if the attendance data is not available for the entire period, a period shorter than a calendar year; and (2) the average attendance at agricultural fairs in the state for calendar year 2020. As a condition of receiving a grant, recipients shall agree to (1) prioritize supporting agricultural fairs in the state facing the greatest financial hardship, and (2) use not more than 5% of grant funds for administrative costs incurred in providing support to agricultural fairs.