This fungus looks bad but does not harm the plants. It feeds on the decaying woodchips. The slime mold disappears when the weather dries. Reduce and eliminate the problem by lightly raking the mulch during extremely wet periods. Convert brush and branches from pruning into woodchips with the help of a chipper.
Many rental companies have chippers.
You and your neighbors may want to rent a machine for the weekend to handle all your brush. Many neighborhoods are cooperatively buying chippers. This reduces the cost for an infrequently used piece of lawn care equipment. Before using any equipment, read all operating and safety instructions. Woodchips make a good mulch for trees and shrubs.