If I play Burying the grudge at the begining of my turn, does it work until the end of my turn? for all my units that will enter to the discard pile?

No. It says "entered", and only refers to units that entered the discard pile before it resolves. If it was a constant effect like you were saying, it would say something like "until the end of the turn, gain 1 resource each time a unit enters the discard pile"

Thank you very much for your help Entropy