On a stove, heat 2 cups of water until it's almost boiling. Remove it from the heat, and steep your mushroom in the water for several minutes, stirring occasionally. Strain out the mushrooms. Then mix the contents of 1 packet of your favorite flavor Jello with the water and refrigerate until it hardens. If you want an even more potent (albeit less tasty) treat, try stirring in chopped up mushrooms when the Jello starts to thicken (usually around 1 1/2 hours after being put in the refrigerator).