Communication is always a good start.

What a novel idea. Even though that is the best thing to do my sick mind didn't think of that! haha!

I'm having a similar communication conundrum...how do i tell my neighbors on one side of me please have their children use the road instead of my yard to cut thru to their grandmother on the other side of me. My yard is not child safe...remember from another post that i have nightshade growing in my yard. Plus today one of my gas hatches on my car was open and the gas hatch on my truck was ajar both on the path the children take. I know they were not open this morning when i mowed, nor yesterday when i was pulling weeds in that area. To make matters more complicated they are related to me. So i think your chat with your neighbor might go a little smoother than the mine is going to go. Good luck.

Maybe find/ make a decorative sign denoting wildflowers for that area.

I just can't believe anyone would do that. Agree with writersblock that he thinks they are weeds since that kind of plant spreads easily. People can be very protective of their lawns! Do you have another area in your yard where you can plant the wildflowers? Can you choose another non invasive type of attractive planting to use on the road?

When you say "along the road," do you mean the swale? If so, be aware that you may well be in violation of the reqs for maintaining that area, if you are in a HOA. A lot of them require it to be grass, mowed.

https://www.amazon.com/Wildflowers-Colorful-Sign-Natural-Personalized/dp/B06XP5Y7PC

My FiL would catch cars with rocks when they drove on his grass. Round rocks that were not big but that would lift the car. I would take my floor jack over and help them leave. Put rocks that eat mower blades and you wont have any more problems much.

People etc. doing unwanted things on your property need to be fenced out.

Africanized bees would be more fun to watch.

I agree that the neighbor probably thinks they are weeds. Are they so tall that they block his view as he backs out the driveway?

And I agree that you need to make extra sure you have planted them on YOUR property, not the city's right of way or easement.

Many think the often quite limited way they see things is all there is. I once arrived at a municipal street tree planting of a comparatively rare Japanese cherry cultivar in time to view the exquisite ~peak bloom of the trees. Only to have a duffer in suspenders and a WW II flat top military style hair cut immediately pop out of his tiny house with a small closely mowed lawn (and little else) to ask eagerly if I was there to cut the trees down.

You see, the fallen flower petals drifted onto his grass every year - and he of course just had to come out and blow them off of it.

Probably every day.