Southwest Airlines, Jetblue and Delta Airlines have round trip airfares travelling to and from Boston (BOS) and Nashville TN (BNA) for $128 including taxes and fees. This is nonstop service. On Delta Airlines, it is a basic economy fare so choose Southwest or Jetblue.
Late Aug thru March 6, 2019, select dates, mostly mid-week until Dec-March where there's wide and good availability (except during the holidays)
Use dates and book it on Expedia [expedia.com]
, Orbitz [orbitz.com]
or Priceline [priceline.com]
to see which airline comes up for you. Go with Jetblue as your first choice. Or if you have checked bags, go with Southwest [southwest.com]
because you're allowed two bags checked, for free.