This is number two of two Oxalis plants I own. The other one is Oxalis 'Iron Cross' and this one is named Oxalis 'Charmed Wine.' The name 'Charmed Wine' is a trademark of a gardening company called Proven Winners that supplies these to Home Depot where I picked up this plant.
Chicory (Cichorium intybus) is another common weed found in Chicago. It can be spotted growing alongside roads and in empty lots throughout the city. It is a bushy perennial that is native to Europe but has naturalized in North America. In Europe it has a very long history as an herb with various uses in the kitchen and as a medicinal plant.
Here's another weed that is common in the Chicago area and that grows in my garden. It is called the Asiatic Dayflower and has a true blue color. This is another weed that holds a lot of memories because as a kid we called it "Mickey Mouse flower" because of the two blue petals that sit atop.