Free fishing days is to encourage those that do not fish to get out there and give it a try. On these days, you will not need to buy a license to get out there and give it a try. The following dates and links are for all New England states and information for their respective free fishing day or days. Please note that the individual states may place certain restrictions and/or other regulations.
Connecticut
CT offers 2 free fishing license days Sunday June 16 and Saturday Aug 10 (you must get the free one day license)
http://www.ct.gov/deep/lib/deep/fishing/anglers_guide/anguide_part1.pdf
Maine
Free Fishing Weekend in Maine is June 1-2
www.maine.gov/ifw/fishing-boating/fishing/laws-rules/laws...
Massachusetts
First Saturday & Sunday in June 1-2 (Freshwater). Fathers Day weekend June 15-16 (Saltwater)
http://www.mass.gov/eea/agencies/dfg/dfw/education-events/calendar-of-events.html
New Hampshire
First Saturday in June-1st
https://www.wildlife.state.nh.us/fishing/free-fishing-day.html
Rhode Island
First Weekend in May. May 4-5 (Freshwater Fishing only)
http://dem.ri.gov/programs/fish-wildlife/huntfish.php
Vermont
Second Saturday in June- 8th
http://www.eregulations.com/vermont/fishing/license-information/