Gardeners are often concerned when they see fungal growth in the soil. The growth is generally white and may be thread-like, cottony or crumbly. We are so used to fungal organisms causing diseases we forget how beneficial most of them are. The white stuff is a beneficial fungus that is decaying the organic matter you put into the bed. These fungi, called saprophytic fungi, do not attack plants or cause plant diseases. They feed on dead organic matter, like mulch, compost, soil conditioner, etc. They are critical to soil health. They are one of the primary organisms that break down raw organic matter into humus and release essential minerals to plant roots. The white fungus you see growing in the bed is a friend. Just rake it into the mulch pile and you are "good to go"!