The fungus among your son's azaleas is Fuliigo septica, a slime mold commonly called 'dog vomit' fungus. The different colors and shapes are simply different manifestations of the same fungus. This fungus typically enters the landscape as woodland spores in/on the mulch. When weather conditions are appropriate, such as this spring, the fungus sporulates and puts out its 'fruiting bodies'.
The fungus is harmless to the plants. It will deteriorate as the weather changes.