Originally Posted by echinosum

Your pictures are out of focus and I can't see what it is.

If it is mushroom/toadstool type fungi, there is very little you can do about it. They do very little harm. Best considered an attractive decoration, like having the benefit of the flowers of weed plants without cost of their invasive leaves and roots. If you don't like them, just remove them, eg, with the lawn mower. The quicker you remove them then the are less likely to spore and spread, albeit that some fungi can live for decades underground without needing to spore. See Saprophytic fungi / Royal Horticultural Society

If however it is dog lichen or similar Algae, lichens and liverworts on lawns / Royal Horticultural Society then that is due to poor drainage.