I know absolutely nothing about dream interpretation but I thought I would take a stab at this. The way I imagine this scene is some brown leaves around, patches of frost on the ground, you are on the right side, your son on the left. The snakes crossing your path is like a river, a black river. The black river represents the flow of your life in the past, especially your childhood. Now you are on a different path and you are no longer polluted by the experience of your past. You look at the snakes with no fear, they are no longer a part of your experience, but you still don't want to walk over them because you don't want to pollute yourself with the past.