I'm not a graphic artist so I can't draw for you but think about this....
A river meandering through a grassy plain, fields of something growing next to muddy banks, add in some things that North Dakota is known for (Bison, Oil wells, etc...). I travelled through ND years ago when I was a kid and I seem to remember rolling hills in the Bismark area, you could probably work those into the background.
I think I would do the words Muddy River Masher's in a brown font and if you could make it look squiggly/drippy that would totally kick butt.
Seriously, I wish I could convert my visual images into something on a computer, but my 6 year old daughter is a better artist than I am.