In my lawn I found some mushrooms that grow clumped, are tan/white, and appear to be hollow. When punctured a LOT of brown "dust" rises into the air. When I used the hose to add water (thinking the "dust" would settle) MORE "dust" rose, and the "dust" does not dissolve but repels the water. After the "dust" that spews forth, the rest of the mushroom seems to be a hollow container. Is it poison??
The mushroom looks like a puffball. It is dispersing it's spores. The spores are not toxic. But, some individuals may be allergic to the spores. (It is a fungal fruiting body.) If it is a true puffball, the mushroom also is not toxic. There is another fall mushroom that looks a little like a puffball that is toxic to most folks. Fresh puffballs have a white tinder skin and white flesh that gradually turns yellow to yellow-green and dries to the spores that you see. It is always important to properly ID any mushroom before you use it. Do not use any mushroom that you are not entirely sure that it is safe to use.
See our Missouri Dept of Conservation site for more information on the puffball mushrooms. You may have similar information in your state.