The problem with invasive, or alien, species is that they often crowd out the native plants on which wildlife depends for food. Their strategies for success include a long growing season, deep tap roots for obtaining water, and chemicals that inhibit neighboring plants from thriving.
If you find garlic mustard anywhere, please remove it as follows:
1. Either cut the stem below the point where the leaves and stems emerge from the root (the crown). This has the advantage of not disturbing the soil and thus encouraging buried seeds to sprout.
2. Or just pull it up.
In either case, if you think the plant has seed pods, please discard it in your trash.