I haven't done it in a while, but I've planted winter forage for my birds.
That was a mix of a deer food plot seed, a bag of feed store oats, and about a pound of turnip seed. The plot was 45ft x 90ft.
This is it about a week later:
When I do it again I'll skip the deer food plot seed mix as it did not perform as well as I'd hoped. Feed store oats, maybe some feed wheat, and the turnip seed. Keeping it well watered until it established was the only difficult part as it was pretty dry that year. Keeping it irrigated after you put the birds on it will extend its usefulness.
There were two tractors of birds that time on the forage.

That was a mix of a deer food plot seed, a bag of feed store oats, and about a pound of turnip seed. The plot was 45ft x 90ft.
This is it about a week later:

When I do it again I'll skip the deer food plot seed mix as it did not perform as well as I'd hoped. Feed store oats, maybe some feed wheat, and the turnip seed. Keeping it well watered until it established was the only difficult part as it was pretty dry that year. Keeping it irrigated after you put the birds on it will extend its usefulness.
There were two tractors of birds that time on the forage.