I have a blue corydalis in my garden which I have deliberately planted! I think they are lovely! It grows really well in my city - the yellow form - lutea - in particular, pops up in front gardens all over! So it does spread (via seed I think?) but it's not the worst offender by a long way - and I think it's native. Provided you don't mind removing the seedlings, which is really easy to do, it's quite easy to keep in check.