Lowe’s and Home Depot sell bags of wildflower seed I had success just tossing it over the bare soil.

Do you have a tiller? Till the soil at a shallow depth to pull up the new weeds and seedlings, then broadcast your wildflower seeds right after. That will put your seeds and new weed seeds at the same growth stage. https://articles.extension.org/pages/18882/knock-weeds-out-at-critical-times

Alternately, spray the weeds with herbicide then broadcast your seeds.

Give this a read for a bit of perspective http://lweanerassociates.com/?p=1203

I had a small field that was never mowed. One summer I tossed a bunch of extra Sweet William seeds around in the tall grasses and forgot about it. It bloomed beautifully the next summer.