^ DO NOT GO INTO PEOPLE'S FIELDS WITHOUT PERMISSION! That is called trespassing, and may well (and should) get you arrested. I live on a horse farm, and at least once a year, we get some idiot who does this. They almost always end up thinking the mud hole in the corner is a good idea, and get stuck. Some abandon their vehicle (stupid), and some come ask for help getting it out (slightly less stupid). All of them ignored the "No trespassing" sign.
Many state parks (by the way, you didn't mention what state you're in- get this thread moved to your region of the US for some better results!) have some dirt roads, mud, and trails for 4x4's (again, make sure it's legal first). People who go trailblazing are the ones who get legal trails shut down- NOT COOL!
So there's my first rant of the day down