Hi Michael, looks a bit like really fleshy, extremely well fertilized wandering Jew!
Actually it looks like you might have a few edible weeds coming up down there.
Wandering Jew is edible in small amounts fresh in salad or larger amounts steamed to remove the phytotoxins.
Or you could just carefully lift it out of the soil and add it to your weed tea, not the compost bin where it will continue to grow and proliferate. Any small root piece left in the soil will regrow so do it now while the corn is young. Use a garden fork or weed lifting tool so you don't break the roots. They'll be white and fleshy with corm down several centimetres and more roots beyond that.
I found a tiny amount of wandering jew a few years ago and sadly did not eradicate it totally at that time. Now it is coming up everywhere. If that is what your volunteer is I can only suggest getting rid of it as soon as possible.
I've had to learn to live with prolific Wandering Jew. I just smother it with cardboard, paper and leaves and cow/chook poo every time I replant the vegy garden. I let my friendly cows out occasionally and they LOVE Wandering Jew as do my chickens when the pinto peanut (their absolute favourite) isn't flowering.