Hesitant Mulching

I live in the city and I want to collect local tree cuttings and use it as mulch. For whatever reason I'm always hesitant because 90 percent of the time I dont know what kind of tree it is that ill be putting in my garden and whether or not it has allopathic qualities. Is there anyway of testing this? I really want to tap into this unused goldmine of mulch.

Where are you?

Trees have leaf shapes which are distinctive and recognizable.  An oak tree can be easily distinguished as can walnut.  Images are readily available online.  The bark and shape of a tree can also be used to identify the tree.