efloraofindia:”For Id 21092011MR2’’ mushroom Pune: One query. Whenever mushrooms are posted for Id experts ask for a pic of the underside of the mushroom. Why is it so important. I fear touching these wild mushrooms as I have heard they are poisonous. If I have to take the pic from below then I need to uproot it with a stick which my conscience does not allow me to do so. Fortunately this mushroom was already exposing the under surface

This is probably some species of Agaricus. The image of the under-surface of a cap in mushroom is very important for identification of a mushroom.
Identifying mushrooms are quite tough its nearly impossible to do even with best quality images even the colour of the microscopic spores can change the species. There is no worries to about toxicity of mushroom if you are toughing them, even the most toxic mushroom will have no effect on you if you touch it the poisoning only happen if you ingest it.
check the website from the link hopefully it will answer your queries better.

Thank you so much … Now I will have no fear to touch the mushrooms 

To identify mushrooms one need to know many things about the sample.
What the cap. the stem etc. look like. here
http://en.wikipedia.org/wiki/Mushroom  you will find the Morphological characteristics of the caps of mushrooms.
Also the base of the mushroom is important to identify it. so turn the mushroom out of the soil, to get the whole mushroom in your hand. Mushrooms are surely poisonous, but no harm in touching it. I have even seen mushrooms specialists, cutting a tiny tiny part of the mushroom und tasting it, but not swallow it. As Tanay says, poisoning only happens if you ingest it.

This not Agaricus augustus because the suggested species has an annular ring which missing in your mushroom.
To know different parts of a mushroom kindly flow the link below

Surely identifying mushroom is tough but there are some obvious ones which can be identified easily. 

Is it Agaricus species ?

Termitomyces seems more likely.
Was the base rooting?