Good or bad you be the judge

This area has a ton of what I think is yellow Crown Vetch growing wild but the city has also seed some empty lots with it. It spreads fast and crowds out weeds- I know looks aren't everything but will let you judge 1st picture is a huge field on the edge of town along a main highway and the other an empty big weed filled field. Some say it is agressive but I have heard some say invasive- I don't know which but love the look and it blooms all summer July to freeze. My dad wants to rip out the lawn on the boulevard and seed this in- any suggestions? Thanks Kathy

It's really hard to tell from the picture, but could it be bird's foot trefoil? It's not native, but then almost none of the plants that we use in our lawns are - even good old Kentucky bluegrass is introduced from elsewhere. Cows like bird's foot and it is raised as a forage as well as a lawn plant.

This is a close-up of the plant.

Yep, that's bird's foot (Lotus corniculatus). Our farm was chosen to grow a test patch of a new cultivar for use as a haylage/hay plant. We had a total crop failure - it really doesn't like heavy soils. It is a legume, fixing nitrogen in the soil, and a high energy plant when used as forage for cattle. It is European, but I don't think it has ever been thought of as invasive. Not all aliens are bad.

By the looks of that, I think you may have answered your own question. That has definitely "naturalized".

It's deemed invasive-
http://www.dnr.state.mn.us/invasives/terrestrialplants/herbaceous/birdsfoottrefoil.html

Birdsfoot Trefoil. I love the color. We planted some under a silver maple years ago. It looked good for a few years, but it ''throws'' seed, so while the original slowly died out, it was spreading farther. It wasn't behaving anymore and didn't look nice, so we eliminated it. They plant it along highways here. It looks better in the ''wild.''

It will take over if it has the hot dry sunny condition it likes.