The Millrace Festival of Traditional Folk Music, in Cambridge August 3-5 is the biggest Local Festival. Check it out. For info go to http://www.millracefolksociety.com/
In addition to lots of concerts and work shops featuring top musicians from a wide variety of traditions there are dances, playing sessions and sing-a-rounds, all in the beautiful downtown Galt area of Cambridge. Plus it is free of charge. So, check it out, buy a program, make a donation, sing some songs and join the Millrace folk Society.