There are literally bazillions of fungal microbes per cubic inch of soil. There is nothing you can do about it. The mushrooms only mean the soil is a little too moist for the grass. If the mushrooms are growing in a circle you might want to keep an eye on the grass inside for signs of browning. Normal soil must have a healthy population of bacteria, fungi, microarthropods, and protozoa. If the microbes become challenged by lack of air or too much moisture, the beneficial microbes can shut down leaving the door open for the pathogenic microbes to cause diseases. When you get mushrooms they are normally harmless. Even the really ugly stuff, like dog barf fungus, is harmless. But some of the pathogens cause lawn disease. Using a fungicide when you don't have a problem with the grass is not advised because it can knock back the population of beneficial fungi. Those beneficial fungi are known for giving soil a fresh aroma when you dig it up. They are also known for causing moist (not soggy) soil to feel soft when you walk on it.

Where do you live? -need to narrow down your climate and general soil type

What kind of grass do you have?

What is your watering schedule? How often and for how long do you water?

How high/low do you mow and how often?

When were the last two times you fertilized and what did you use?

We are in south central British Columbia, the climate is hot dry summers and generally mild winters. Our soil is heavy clay with winter grasses. We were on severe water restrictions this summer so the lawn got watered for a few hours in the evening once sometimes twice a week. I was leaving the grass about 1-1/2" in the spring, 2" in the summer to keep it from burning and cutting weekly. I have not fertilized.

I am very familiar with 'fairy ring' and the damage it can do, I saw a lot of it in the years I lived in Edmonton Alberta.

Circular mushroom patterns are always called fairy ring, but not all fairy rings are evidence of a problem - at least not in my area. Sometimes it's just an interesting curiosity.

I don't know how severe your water restrictions are but we were only allowed to water during a designated 7 hour period, once every 2 weeks, with temps in the high 90s in San Antonio in 2014. We got through it by following what is becoming a 'normal' maintenance plan.

The mantra for proper watering is deep and infrequent. Deep means 2.5 to 3 cm of water all at one time. We use tuna or cat food cans placed around the yard to time how long it takes to fill them. That will be your watering time forever. Infrequent means you allow the surface to dry out completely before watering again. What seems to work is going by air temperature. With temps in the range between 32 degrees C and 38, you should water deeply once per week. With temps between 26 to 32, water once every 2 weeks. With temps between 21 and 26, water once every 3 weeks. With temps lower than 21 you should water once per month. This works just about everywhere.

Mowing height should be at or near your mower's highest setting. 4 inches is great. Tall grass grows deeper roots which can withstand the dry conditions much better.

Fertilizer. I'm not sure why you don't fertilize, but when you get onto the watering and mowing program above, you might really never fertilize. Generally changing the watering and mowing taller produces much healthier and greener lawns. If you decide to fertilize, the times to do it are late spring (after the spring flush of new growth), early fall (after the summer heat breaks and evenings cool down), and late fall (after the grass stops growing but before it goes dormant). I like organic fertilizers like corn meal, alfalfa pellets (rabbit chow), soybean meal, cottonseed meal, etc. Apply any of those at a rate of 15 to 20 pounds per 1,000 square feet.

Here is a picture of a lawn following the practices above along with some who are watering daily.

That is an interesting read, thank you for your suggestions. We didn't fertilize because we moved here in May, I spent most of my adult life in apartments and condos and know squat about looking after lawns.

Basics of Lawn Care

After reading numerous books and magazines on lawn care, caring for lawns at seven houses in my life, and reading numerous forums where real people write in to discuss their successes and failures, I have decided to side with the real people and dispense with the book and magazine authors. I don't know what star their planet rotates around but it's not mine. With that in mind, here is the collected wisdom of the Internet savvy homeowners and lawn care professionals summarized in a few words. If you follow the advice here you will have conquered at least 50% of all lawn problems. Once you have these three elements mastered, then you can worry about weeds (if you have any), dog spots, and striping your lawn. But if you are not doing these three things, they will be the first three things suggested for you to correct.

1. Watering
Water deeply and infrequently. Deeply means at least an inch in every zone, all at once. Infrequently means monthly during the cool months and no more than weekly during the hottest part of summer. Do not spread this out and water for 10 minutes every day. If your grass looks dry before the month/week is up, water longer next time. If that does not work, then you might have to water more than once per week during the summer's hottest period. Deep watering grows deep, drought resistant roots. Infrequent watering allows the top layer of soil to dry completely which kills off many shallow rooted weeds.

You will have to learn to judge when to water your own lawn. If you live in El Paso your watering will be different than if you live in Vermont. Adjust your watering to your type of grass, temperature, humidity, wind, and soil type. It is worth noting that this technique is used successfully by professionals in Phoenix, so...just sayin.' The other factors make a difference. If you normally water 1 inch per week and you get 1/2 inch of rain, then adjust and water only 1/2 inch that week.

2. Mowing
Every week mulch mow at the highest setting on your mower. Most grasses are the most dense when mowed tall. However, bermuda, centipede, and bent grasses will become the most dense when they are mowed at the lowest setting on your mower. In fact there are special mowers that can mow these grasses down to 1/16 inch. Dense grass shades out weeds, keeps the soil cooler, and uses less water than thin grass. Tall grass can feed the deep roots you developed in #1 above. Tall grass does not grow faster than short grass nor does it look shaggy sooner. Once all your grass is at the same height, tall grass just looks plush.

3. Fertilizing
Fertilize regularly. I fertilize 5 times per year using organic fertilizer. Which fertilizer you use is much less important than numbers 1 and 2 above. Follow the directions on the bag and do not overdo it (unless you use organics in which case you may overdo it without fear of hurting anything).

At this point you do not have to worry about weed and feed products - remember at this point you are just trying to grow grass, not perfect it. Besides once you are doing these three things correctly, your weed problems should go away without herbicide.