Bit of a surprise

I try to be very careful when growing mint, it spreads like wildfire, so I keep them in pots.
I bought some interesting ones last year, pineapple, buddleia and another one that now has no label. This year all three are doing well in the herb garden but still in their pots.
The surprise is this flower that has grown in one of the pots. It is very short, not a lot of space to grow presumably, but it seems to be a self seeded sunflower.
Not my plant of choice in that position but it has brightened up a little corner rather nicely