As part of the performance of Gaya shraddha, we stop partaking certain vegetables, fruits, etc. If the vegetables and fruits that were renounced are included in prasadams given at temples or Mutt, can we partake that prasadam? Or must we not accept them? If we had unknowingly partaken such a prasadam, is there any atonement?

The vegetables and fruits that we had renounced during the Gaya shraddha, must not be partaken even if they are given as prasadam. There is no specific atonement for partaking the renounced substances as a prasadam. Having realized that we have partaken renounced substance, we must mentally seek forgiveness and be mindful not to repeat it.