OK, , YES I have tried mixing in buckwheat in with beans
and yes it will grow,
but its down fall is that, well, you cannot do weed control with roundup type sprays once the seeds are planted
secondly the stuff gets tall, and will die before deer hunting season, making a lot of nothing come fall
sure the turkeys and deer will love it while it grows
but it does make a lot of junk to get rid of, if you are thinking about reseeding the same plot come fall for, say adding brassicia to the beans latter on
buckwheat is a great plot don't get me wrong, it does help keep soils soft /easy to turn over again and its cheap seed, and dopesn't need a ton of great soils or fertilizers to make feed!
in that article, I sent you they did touch on buckwheat too!
I personally think the best thing to add to beans is nothing till late july mid august( I do add corn , simply for a little cover, but never get any ears)
, keep the beans as weed free as possible till then, then wait till a good SOAKING rainfall and near the end of it , just seed the plot with brassicia' or likes!
(rape seeds are more or less same, most don't make a bulb however, but are cheap and make a ton of fall, winter feed), sugar beats purple top turnips etc.!
, or even oats, ( but if soils is very hard, don't do oats, there too big a seed to work well just re seeding them!
or any some what small type seed will plant it self in soaking rains pretty well!!
the rain will more or less plant them, the beans will help work to protect them till what ever grows some
you can still broadcat fertilizer on top of the seeds too to help(do a soil test first if doing a BIGGER sized deal to not spend more than needed or, not enough)
but
feel free to experiment,
most things will grow, and deer / critters will eat almost anything that grows, where I Plant! they sure do! !
good luck