Litter also insulates, limiting soil warming. Layers over 3 inches seldom receive the warmth needed for formation. In soils such as pumice, needles and soils mix together forming this layer. Fruit formation is from 1 to 6 inches from the surface. As the mushroom grows, it pushes up the soil and litter cover, creating raised areas or bumps.
Bumps usually indicate an older mushroom.
Study each foot of ground around the bump. Get down on hands and knees and feel the ground. Push down on the litter with your hands. You will be able to feel other mushrooms. Don't worry about missing some, you will feel them before they are large enough to harvest.