Description:
I think it is Bombus griseocollis but t may perhaps be Bombus impatiens or Bombus bimaculatus. These three Bumble Bees are the most common species in the eastern part of the US.
Top & Left: Gilsland Farm Audubon Center, Falmouth, Maine, USA, 7 August 2017
Middle, Right & Last: Falmouth, Maine, USA, 6 August 2017