I have a Murray 30" and every time I try to start it, it spits gas out of the filter and the muffler. Any ideas?

You have a stuck float, or water in the carb... probably a leaky inlet needle...

Best thing to do is not run it till its fixed... drain that oil!!
Drain the gas, take the fuel bowl off the carb, and check and make sure the float is operating freely.. there's no corrosion or water in there, and the inlet needle looks OK... also make sure the float isn't heavy... they can spring a leak around the solder and fill with gas.