I have mushrooms growing out of my lawn.

You can rake them off, pick them off by hand, or run the mower over them. They are due to damp weather, and there is no chemical that stops them appearing.

Welcome to GOY and as Spritzhenry says - you can't stop mushrooms and toadstools appearing - especially at this time of year when it is damp but still mild. If they bother you - or you have children you are concerned for - just pick them off....otherwise just ignore them ..they will just disappear!