The Minnesota Department of Agriculture has issued a press release again this year, asking the public to report infestations of Garlic mustard (Alliaria petiolata) and remove the species when possible. Unfortunately, they don't include a good link to a page with more information on how to identify the plant or control it; you can go here for more information.
Garlic mustard is a biennial, meaning that it does not flower in the first growing season, making identification more difficult. The leaves do emit a strong odor of garlic when crushed, but after making the mistake of doing this with what turned out to be very early growth of Stinging nettles (Urtica dioica), I recommend you use something besides your hands to crush the leaves. Since Garlic mustard flowers early in the spring, to remove second-year plants before they set seed you'll have to attack within the next few weeks. It's unclear exactly how the seeds are spread, but I suspect humans play some role in their distribution when they tromp through infested areas.