Hi everyone. Can anyone tell me the name of the purple flower?

And...is it possible that it self-sows? I swear I did not plant this flower/seed this year, nor did I buy any plants like this. So I wonder if it's in fact from LAST year and it self-sowed, and into multiple of my containers. Because all of a sudden this summer, this little purple flower popped up in multiple of my containers (which I was happy to see....). ;-)

Thanks!