You can almost always get free seed from your local Pheasants Forever Chapter. I am the immediate past treasurer of the Ingham County Chapter and we give away approx $20,000 worth of seed every year. That is what those banquets you probably hear about are for. Our chapter in the past has given away corn, sorghum, buckwheat, japanese millet, 7 types of clover, field pea, sunflower, and others that I can't remember. Some of them are mixed together into a blend that gives a little of everything. There are perrenial nesting cover mixes as well as annual food plot mixes.
As far as restrictions, we only ask that you plant it and not leave it in your garage/barn, that you sign an agreement not to harvest it, and that you let us come by to take a look at it. This lets us bring some other potential cooperators to show off the habitat successes or take pictures for presentations. In reality we rarely ever show up. There are NO other strings attached. There are NO minimums and usually no maximum allotment. You do not have to allow hunting on the property at all let alone any PF members. We have city dwellers that like to put in a garden size plot to farmers or hunt clubs that put in 40 acres.
If you have any other questions please ask. All PF chapters have a solid committment to increasing wildlife habitat. Most if not all chapters will consult free of charge to help you improve your habitat for whatever species you want to hunt or just plain look at.