Look up dog vomit fungus. It's not really a fungus but a slime mold, harmless. It's decomposing your mulch. With dry weather it will disappear.

So, I should just leave it alone and go about my business?

Mike, you have good nerves not to freak out seeing that on your corn! Impressive slime mold! I found a lovey hot pink one in the woods earlier this year, I always have newfound respect for the variety of life on this planet when I come across one of those, in any color. It isn't likely to hurt that corn plant and may in fact help a little by freeing up some nutrients from the mulch. Just let it dry out and it will disappear on its own. It's probably ending its crawling cycle now and has climbed up to better spread its spores on the wind. Cheers!

Thanks for the reassurances, but I did freak out a little. lol From a distance it looked like the corn plants were starting to explode with buttered popcorn. I don't recall ever seeing anything quiet like that.

"From a distance it looked like the corn plants were starting to explode with buttered popcorn"

LOL -- what a wonderful image!