plant natives to the area.

Find native plants in your area. Meadow flowers are probably a good place to look for cheap sources of seeds.

Mix the seeds with something that you can form into a ball. Garden soil might work well but it depends how much clay is in your soil. If it is too crumbly you could try adding clay or just use clay on its own.

Once formed into balls, yeet them to deploy! Optionally you may want to let them dry out a bit first. Could throw them, or a staff sling could be fun. I suspect it would help to make and launch them shortly before heavy rain so they get a good start with moist soil.

I don't have a recipe, though there is a wikihow. I just wanted to stop by and remind you that you should never, ever throw your seed bombs over a fence into private property that is reserved for future construction as a way of beautifying areas that very obviously have no caretaker, because it is private property and not an eyesore you have to walk past every day.

FYI, children make an amazing force multiplier for seed bombing. Not only do they love making them, adults are a LOT more forgiving if they deploy them in inappropriate places.

Also, if you present it correctly a lot of groups like the scouts would jump on helping. It's a fun activity for the kids, as well as great for the local environment. The kids involved can also be STRONGLY self motivated to make and deploy them in large numbers. They have several badges that this could be fitted towards getting.