While I agree that I know of no poisonous puffballs some caution is still necessary in picking them. While puffballs are good if the insides are all white, poisonous amanita buttons can resemble puffballs and may be found in the same areas. Make certain that the mushroom you have picked is solid inside. The amanita button consists of a veil or skin over a stemmed mushroom that will eventually break through the veil. Slicing one of them will reveal a hollow bulb with a stem and gilled cap inside. They really are not hard to tell apart but I wanted to emphasize this for anyone who hasn't picked mushrooms before and doesn't have access to a field guide.