1st how to get the 3rd mushroom
2nd does the game have end?
1: Go to the northern map squares and wait for about 10 seconds without pressing any buttons. If there are any Ghost Caps they should pop up.
2: Kinda! If you get 5 Mushrooms of each type you can go back to each character for some special dialogue. Otherwise if you have at least 1 of each mushroom you can go back to the witch hut to roll credits.