Experts and BHG readers answer.
mushrooms and white stripes
Mushrooms are not a sign that anything is amiss. When conditions are moist for extended periods,they often show up. They do not harm the lawn. You may wish to pick them out by hand if you have small children that might eat them, however.
The white stripes are a little tougher to diagnose. The only thing that usually causes white color on grass is powdery mildew, which bluegrass can get sometimes. If that's what it is, it typically requires no treatment.