Forgive me if this discussion is elsewhere on the site, but I couldn't find anything.

Guy orders hay from out of state, (I have three or four potential victims). Hay is delivered and paid for in county. Check is NSF. I say theft, but am concerned about "worthless paper". Any ideas out there?

(In at least one case, a shipment of hay was returned, but it was not the hay sent originally and the hay was substandard.

What you probably have is a theft. The qualifier is because I am making some assumptions. I assume that the transaction was a COD transaction, that the check was not postdated and that the complainant left the hay there because he was led to believe that he was being paid for the hay rather than being stuck with worthless paper.
I also assume that you have done(or have had your complainant do) what is necessary to establish the 31.06 presumption and reviewed the relevant bank records to be confident that the defendant knew the check was bad.

You would have Issuance of a Bad Check if the check was written only to comply with a promise of future payment rather than to induce delivery of the hay.