You are talking about a native patch in a non-native yard. That's not how this works. You make a native YARD. The fact that they spread seeds is a GOOD THING. It's not a weed, because it belongs there.
It's self-seeding, it's self-maintaining. It's not magic, it's evolution. The plants are supposed to be there, they want to be there, the ground wants them to be there, nature wants it to be there. You're building a house in nature, not putting a tiny spot of non-natural nature in your lawn.
The maintenance is less, but you still have some. You just need to make sure that invasives stay out, but past that, it's mostly self-maintaining.