I plan to do this as long as I can and would encourage others to do the same! I was amazed by the difference.
I've noticed that Monarch butterflies ignore almost all plants in my area but they love Mexican Sunflowers (Tithonia rotundifolia). I wonder how much of that is regional, since they're supposed to like Zineas and Verbena but they've shown zero interest in mine.
It looks like queen anne's lace--crowns of many tiny, white flowers. We have a few similar-looking species in the region (Ozarks), and it could be any of them.
Maybe worth a shot finding out if you want some other options for them!
[0] https://www.fs.fed.us/wildflowers/plant-of-the-week/asclepia...
In this particular case, though, it was a similar plant that I normally always see in sunny areas. On the edges of my mowed yard, I was seeing a lot of monarchs for a few days.