Those are wild flowers. I don't know the name but there is a gardener down here who collects the several varieties for the color of their flowers. They are members of the lily family and grow from a small bulb that is about 6-8 inches below the soil. If you want to dig them out, that's what you're up against.

I had a few in my yard a few years ago but they disappeared. I suspect they could not stand my watering schedule of once per week in the summer heat. I'm completely organic and have not used any herbicide for...I'm guessing 15 years. So it wasn't anything I deliberately tried to do that got rid of them.

We get wild onion up in New York during the part of the Spring where the grass is turning green but really hasn't started its heavy growth yet. The onions take off like crazy and can grow 8-9 inches in a week if conditions are right. Despite the fact that many cooperative extension and websites claim that 2,4-D (Weed-B-Gon and other products) work on wild onions and wild garlic, my experience is that unless you break the waxy cover by scratching it with one of those pot scrubbing pads that is dipped in 2,4-D (wear rubber gloves!!!) it just doesn't work well. I have just found that if I mow them down every week or more, once the grass is established and it warms up a bit, they are gone until next early Spring. When mowing, you'll definitely smell that onion smell !!
It sounds like you may have way too many for the "ol' scratchy pad" treatment. You can mow them and forget them, or google "wild onion control" for other coop extension recommendations for herbicides that supposedly work - I just can't recommend them since I have no experience with them.

I can't find them in my lawn once May comes along, and they never flower in my lawn. Since I get them in the same spots every year (back near a woods) and they don't spread in my lawn, I just tolerate them for a month.

Good luck!