Would you mind sharing your combo? I have tried each combo on all 3 play throughs and none of them have worked.
I just tried it on a new save and it is in fact the same combination. Unless I got extremely lucky the order remained the same. The appearance of the mushrooms change on each new game. You need to eat an Echoshroom, a MindSap, and a Deathcandle in that order. However, if you eat a Dreamshroom you need to start over. Without being able to summon the rain you would have to either guess if the mushroom you cannot identify is a MindSap or a Dreamshroom. Unless you use the guidebook to identify the unknown mushroom to see if it is a MindSap or Dreamshroom.