When folks new to food plotting ask what to plant, they usually mean which BOB seed. I generally ask about objectives and such to get them thinking, but I almost always recommend two seeds. For folks anxious to get dirt under their nails in the spring, I typically recommend buckwheat. Deer use it but generally don't abuse is except in small plots or in very high density areas. It has a very wide planting window. It can handle poor pH and infertile soil. It will outcompete most weeds. It is a good soil builder. For those starting later in the year planting for fall, Winter Rye is my most frequent recommendation by far. It has many of the same kinds of characteristics but deer love it when it is young. Both of these are really hard to screw up. With these two successes under their belts, a novice builds a lot of confidence and can begin experimenting.
And, yes, there are other things you can mix with them and that is fine, but these are the workhorses for new folks and after many years, they are still staples for my program!
Thanks,
Jack