Like so many lawns in the Mid-Atlantic, my back yard has become a war zone - albeit an aesthetically pleasing one. Some previous occupant of my house planted spring bulbs years ago, and Kali and I continue to enjoy the vernal exuberance of grape hyacinths, daffodils, crocuses, and the delicate blue flowers picture above, chionodoxa or glory-of-the-snow (Chionodoxa siehei).
More recently, the extremely aggressive non-native buttercup lesser celandine (Ficaria verna) managed to get a foothold in the lawn. Lesser celandine prefers moist riparian areas, but once it gets established, it will grow in just about any situation. (Naive visitors used to ask me if they could dig up a few plants to add to their garden; I assented, but always warned the folks that the plant would take over anywhere it was planted. I suspect that most people now recognize the plant's aggressiveness because I almost never get such requests any more.)
It will be interesting to see if one or the other of these plants will win this slow-motion combat. I once asked Pennsylvania's premier botanist if celandine really does exclude other plants because it is only a obvious player on the ecological stage for about a month, after which it disappears until next spring. The botanist assured me that celandine definitely excludes other plants. Perhaps there's an unseen, subsurface front in this war as well.