Favored weed patches

One of the odder aspects of our family's lawn is that every year, some weeds are given a month or so to show their stuff - to rise above the lawn and bloom - before returning to mowed anonymity the rest of the year. Right now we have two flowers granted this reprieve - King Devil and bluet. These are both in the backyard, though I am considering whether we can get away with having a similar patch in the front yard, where some yarrow grows but has never been allowed to bloom.

This puts us in questionable legal territory with our township. Weeds, township law states, are not allowed to grow higher than 8". But of course, we all know by now that if I love the plant, it isn't a weed. I assume in the backyard these patches go relatively unnoticed - our next door neighbor has clearly mowed around his bluets for decades - but I wonder what would happen if we let something similar happen in front, outside the flower beds. My repeated tendency - to look up the law and then try to find my way around it - may seem familiar to readers who accompanied us through the acquisition of a variance for our chickens. (And again, why am I surprised when I see this trait in Emily?)

I haven't quite set the yarrow free yet, and there is a tempting bull thistle rosette right next to the yarrow. Should I put a fence around them so they look official? Should I just let them go free and call it professional research? The possibilities are enticing. If suburban teens fantasize about sneaking through windows to go dancing at forbidden bars and clubs, this suburban parent has milder aspirations: sneaking through legal loopholes to let the weedy plants grow tall and flagrant. It might be that I need to get out more.