[Gerald]

Must wheat be sown on prepared ground?

No. Wheatcan be no-till drilled into unprepared ground. Also, overseeding
of wheat or rye prior to harvesting soybeans,
corn or cotton to establish a cover crop is recognized as a

normal agricultural practice

.

I don't know what "no-till drilled" means. Is that using something like a "Sheeps-foot" to press the seeds down into the ground.
If so, looks like you can spread wheat seeds on the ground.....as long as you "drill" some or most of the seeds into the ground.
I know they make a tool to loosen up the soil in your yard. It is a metal drum with spikes ~ 1.5" long. You roll it across your yard. This is suppose to help the grass to grow better.