Weeds have taken over
I Have various types of broadleaf and weird mushroom cap growth beneath my lawn. I also have what appears to be vines underneath my grass connecting weds together. Any help is appreciated!!
Your lawn has a foreign invasive grass known as stiltgrass. It is a very common problem in lawns. Usually the easiest way to tackle it is to apply a crabgrass preemergent in the spring. It will prevent the sprouting of the stiltgrass which is an annual grass just like crabgrass. Search 'stiltgrass' on our websit's search box.
Your lawn looks very sparse. The best time to thicken it up is fall. There is a lot about growing successful lawns on our website. Here is a good start: http://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/HG102-Rev-...
The mushroom is a type known as a star mushroom. Like all mushrooms, it is growing on some kind of organic matter under your lawn. Maybe an old root or part of an old stump. It will disappear when the root or wood finishes decomposing. Here is more about lawn mushrooms and what to do: https://extension.umd.edu/hgic/mushrooms-lawns