Trim the stem of where the puffball attaches to the ground. Inspect the bottom diligently, trimming away any portions that have holes or are discolored. The puffball should be pearly white and pleasantly mushroom smelling, if it is at all yellow, greenish, or discolored, discard the whole thing as it will taste too strong and it beyond the stage for eating. Peel the outer skin from the puffball, then, using a long, sharp knife, cut it into slices or cut it in half if it is large, and cut it into half moons. This is not an exact science, as they’re large, unwieldy mushrooms.