The first thing to notice, before you even pick the mushroom, is what is it growing out of? This may be:
Another question to consider is whether the mushroom was growing near trees. Some species only grow in association with tree roots. They made only appear with deciduous trees, or only with coniferous trees. Some mushrooms are even more particular than that and are associated only with limited number of tree species (sometimes only one type of tree). It will help your mushroom identification if you can distinguish major tree groups and species.
Firstly, you should know the difference between deciduous and coniferous trees. Conifers can be further divided into Firs and Pines
A few important trees to be able to identify are: