I've planted cereal rye/winter rye in late summer along with clover as a "nurse" crop for clover. Deer do utilize the rye, especially in the late season and in early spring as it is the only green around during those periods. I did have a little left over seed last year that I broadcast into standing clover this spring and it did ok. I didn't have a lot of seed left so it was pretty sparse.
If you get a good stand of rye, be cautious when you mow it the following year. I used to mow it around Memorial Day weekend but found that the does left their fawns in the shaded areas of the rye. I walked the rye to check for downed limbs and found three fawns bedded in about a 1/3-acre rye/clover plot. Now I wait until the rye is dead, but still walk the plot.
Rye is a good soil builder, as is buckwheat but I have had better luck with the rye. A Labor Day broadcast of rye, either right before or right after a good rain should work well. I suggest going a bit heavier on the seed rate when top seeding. The turkeys will appreciate it too!