Really great tips and tools in the Tools for Identifying Mushrooms posting. I currently have a little grey mushroom growing in one of my beds in my apartment. Will take a photo later and see if anyone knows what it is. In general though should I just leave mushrooms that pop up alone? I know they help spread nutrients between the plants and do many other helpful things sometimes.
Generally I would agree that leaving them alone makes sense: The mushroom is the fruit of the fungi, the body of the fungi is in the soil (or other substrate) and will still be there even if mushrooms are removed, so not much impact. Identification can sometimes let you know what the fungus is eating; whether it is gaining nutrition from the soil, from dead or live plants, from a symbiotic relationship, etc.