Delta, American Airlines, and JetBlue have round-trip flights from Dallas (DFW) to Boston (BOS) for $137-$171, NONSTOP. Flights August to November. Very few weekends available. Origin/Destination reversible. No Thanksgiving dates.
A Carry-on bag and also a personal item is allowed for free on Delta. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.