Mushrooms

I've been seeing some interesting looking mushrooms growing near our garden. It's funny, they seem to grow like overnight. Is that possible? This one white button mushroom was in the path of where I drag my garden hose. So I would have seen it growing. However, it seemed that literally it just popped up out of no where. And it's no small mushroom. This thing is enormous. I put my garden trowel next to it so you can see the size in comparison.

I plucked it out of the ground, because I have my extended family's children who visit frequently, the last thing I want is for one of the kids to think it's edible. Speaking of, I love love love eating mushrooms and everytime I see a nice mushroom, I always think, wow, I wish I could eat it. I don't dare because I don't know the difference between an edible and a poisonous mushroom. Doesn't it look beautiful though?

This mushroom was growing behind our picket fence behind the garden. It looks similar to a portabello I thought. It was brown and really flat.

My sister sent me this photo. Its a giant mushroom! She was visiting our niece and our brother-in-laws' parents and they had this ginormous mushroom growing in their front yard in Connecticut. Check out my niece's blue clog and her grandpa's loafer next to the mushroom. This will give you an idea of how big this 'shroom is. I googled "giant mushroom" and I couldn't find the name of this fungus. Does anyone know what type of mushroom it is? It's really funky, I wonder if it's edible.