At MNRF there are a couple of a capella groups (DeCantus and the Elizabethean Syngers) that actually do period stuff. Do other fairs have this, or is it just a byproduct of the unusually high concentration of choral groups in Minnesota?
Several of the smaller faires in the Illinois/Iowa/Wisconsin area have madrigal singers at them. Some times it is a madrigal choir from a college, because we have lots of colleges around here. There were even madrigal singers at the Dubuque Renaissance Festival, a very tiny but very nice faire that is a 1 weekend faire in June.
TRF has, or at least *had* a madrigal group playing the lanes when I was last there four years ago. I Madrigali I believe they were called. I picked up their cd of renaissance drinking songs, and play it often as a fall/ seasonal kind of thing. Seems to go somehow. :)
NCRF has a madrigal group, the Musicians Royale. We sing madrigals for the Queen by day and pubsongs for the hoypoloy at night. :)
We (New York Renaissance Faire) have a 12 member in-house Madrigal group called the Queen's Royale Madrigals. This past summer we did 3 sets a day. We went for many years without madrigals and personally I missed having them. Since our members are also full time performance company members, including our Queen Elizabeth, scheduling becomes tricky. I am a madrigal groupie when I visit other faires and always try to attend atleast one performance of any local group. One of my favorites is Larksong from MDRF.