I don't recognise it at this stage - if you want to keep it to find out, suggest you extract it and pot it up separately, before the roots start competing with the roots of your Dracaena.

Looks like bindweed to me, a nasty little critter. If so, suggest you carefully pull the weed and destroy!! Hope that helps.

The leaves aren't heart shaped enough like bindweed leaves.

Definitely not bindweed - apart from the shape, they're too shiny anyway

Thanks everyone ? I'll pot it up separately this weekend and let you know how it develops!

It looks very like a peace lily but don't suppose that's possible?

I'm pretty sure its not Peace Lily, Stera... but its not much use, knowing what it isn't when I'd rather know what it is...

True.