Hi Patrick,

Try spraying with a disk soap and baking soda solution. A spray bottle
should help. One tablespoon of dishsoap to a quart of water, one tsp.
of baking soda. The mushrooms don't like the solution - and the garden
plants benefit from it. You'll have to keep it up over the season, but
if they can't grow, they can't spread. If you get really adventurous
you add 1/2c. everclear - though if you use that you have to be careful
about your plants. The everclear can burn some of them.

Joan Taylor