The license here only says, "The beer to be sold and delivered under paragraph (2) of this subsection shall be manufactured with an ingredient from a Maryland agricultural product, including hops, grain, and fruit, produced on the licensed farm." That doesn't preclude using wheat or another grain as 30% of the grist. As long as you aren't violating the spirit of the law by, say, adding one farm grown hop cone per batch, it seems like it should be fine.