Mushrooms in grass are caused by fungi that thrive in damp, dark environments, breaking down organic matter in your lawn and yard. While mushrooms are not harmful to your lawn, some of them can be poisonous, and you may want to get rid of them for aesthetic reasons or if you have curious children or pets. Here are some ways to kill mushrooms in grass:

1. By hand: Use gloves at all times, as some mushrooms are poisonous. This will only remove the ‘fruit’ part and will not kill the fungi in the soil.

2. Use a natural fungicide such as vinegar: Dilute 4 parts water to 1 part vinegar. Spray directly onto the mushrooms. The acetic acid in vinegar will kill the mushrooms. However, the acid will also kill anything else it comes into contact with. So, be careful where and when you spray.

3. Apply baking soda: Baking soda raises the pH of soil. Dissolve 2 tablespoons of baking soda in a gallon of water and spray it over the mulch. This will help kill any mushrooms growing in the area.

4. Remove the mushrooms: Dig out the cluster of mushrooms with a shovel or spade, at least 12 inches down to remove as much of the fungus as possible. You can also simply mow over them and pick up the mushroom pieces. Toss the mushroom pieces into a trash bag, tie the bag, and throw it in the bin. Do not dispose of mushrooms with your grass clippings or other lawn waste.

5. Remove decaying organic material: Mushrooms often grow in areas where there is a source of decaying organic matter, such as fallen leaves, grass clippings, or a tree stump. Remove any decaying organic material from your lawn.

It is important to note that chemical fungicides are not necessary and might kill beneficial soil agents.