Companion planting by default

I sowed my parsnip seeds direct out in March. By end of April most had taken, but there were a few gaps where they did not germinate, so I decided to sow some more in the gaps. Due to clumsiness I spilt a some seeds in the soil nearby, but as they are so small could not get them up and anyway Parsnips are notoriously hard to germinate, so I thought nothing would happen.
I since planted out my sweet corn on this patch next to the parsnips and netted them against birds. Having now removed the netting I thought I needed to weed as I had seen some weeds come up among the sweet corn. It turns out what I thought was weeds are half a dozen or so parsnips growing on nicely. Checked they have sufficient spacing and will leave them to grow on among the sweet corn as a bonus crop! 

Moral of the story: Just chuck out a load of parsnip seeds on the soil and forget about them!!