I'm pretty crap at IDing weeds I'm not familiar with, but from the 5 ft elevation pictures, I can see you have a serious problem. There are selective plant killers. If you have a grass problem in with your broadleaf plants, then there are selective grass killers. If you have a broadleaf invasion in your grass, there are selective 'week' killers. But there are no selective grass killers to kill a specific grass in among the lawn. Sadly I think this would require a complete renovation, and then what will prevent it from coming back?

You can take a sample of the plant and your pictures to your local county agriculture extension agent. Every county has one...or at least had one up until the latest inauguration. They should be able to help you with the ID and possibly with a cure.

And thanks for telling us where you live. That's important.