List of common alelophatic plants?

I have been picking plants for mulch on my backyard from everywhere and I am worried that I may bring alelophatic (have substances toxic to other plants) to my garden. Is there any site on the web with lists of alelophatic plants? or any way to recognize them easilly (other than having your plants die).

Thanks in advance.

My understanding of alelopathic plants is that they create their toxic substances while they are alive. The toxins would decompose with the plant. For instance , Black Walnuts create juglone which inhibits the germination of some plants. Our annual garden is just outside the rootball of a number of Black Walnuts. In the fall , alot of debris falls into the garden . By the summer , we have no trouble with tomatos , beans , etc. Most plants that are allelopathic have freinds , they let some things grow around them and inhibit others. But by the time they are mulch or composted their allelopathic stregth is quickly waning. Maybe someone else on the forum knows different.