My friend, a farm girl, gave me two big mushrooms she found on her mushroom hunting. She carefully wrapped those mushrooms and placed them inside her lunch bag. It was so sweet of her to remember me. I love many kind of mushrooms, and excited to try the "new" one. She told me that those are Puffball mushrooms. If I identified them correctly, the scientific name is Calvatia cyathiformis or Purple-spored Puffball. The diameter of the mushrooms that I got were about 4.5 inches/12 cm, but they can get bigger than 12 inches (30 cm). They grow in late summer and fall, and can be found in lawns and the woods.
My friend assured me that they weren't poisonous. I did a little research online and found some tips to examine if the mushroom is categorized as toxic. There are some look-alike species that can cause gastrointestinal symptoms and can be deadly. The physical appearance can be too similar for some people (like me), but the inside are obviously different. So, it is suggested by the experts to slice the mushroom open. The interior of the true Puffball composed of solid, white, homogenous flesh and no sign of stalk, gills and cap. For more information, read this and this.
Last night, I eagerly cut the mushroom. The inside was pure white like a white bread, puffy like sponge, and soft like silken tofu. I cooked it with red pepper, garlic, sweet soy sauce, and fish sauce. What a yummy dinner!