Name: Michele Roth N.E. Indiana - Zone 5b, and F (Zone 9b) I'm always on my way out the door..
It does look like a begonia. This year I had what appears to be a Begonia boliviensis sprout in the container my Peruvian Lily lives in. This had to have been dropped seed from last year's plant, so it's quite possible that yours came from the soil you recycled.
