You may want to check out http://corn-freefoods.blogspot.com -- Avoiding corn is a big challenge, and not everything on the list is going end up being safe, but it should give you a good place to start.

Corn Allergy Info:
Cornallergens.com is a great place to start, but you’ll want to head to http://forums.delphiforums.com/AvoidingCorn for better information. There’s also no-corn.blogspot.com and corn-freefoods.blogspot.com

I actually make my marshmallows with a simple syrup (sugar + water heated to softball) since I’m allergic to corn syrup.. they’re fantastic, and work well as marshmallows if I manage to not eat it all before it sets. :)

I also add flavors and coat them with various things such as superfine sugar (think peeps), cocoa, or my favorite cinnamon (taste like red hots).