Well, I have Good News and Bad News.
Good News: Wellshire Farms has an Allergy Database on their website. Which allows you to search for foods without your allergies. HURRAH!
Bad News: For corn its not very accurate. Things listed being corn-free may not be. One person took the list provided to the grocery store only to find the packages claiming corn. Another person reacted to supposedly corn-free items, only to find out later that the packaging is dusted with corn starch.
**** Update: Wellshire Farm's lactic acid culture is corn-based. This information is also not included in the Wellshire Farms allergy-search for corn.