If you’re in the US, I have gotten good results/ seeds from ptlawnseed.com. They have a bunch of different options and tell you what works well in your climate zone!

I just looked up what type of clover grows well in my climate, then every spring, I order a 5 lb bag and just walk around throwing that everywhere. Add some water and let it go nuts. Once clover is established, it starts to spread on its own, but I like to give it more friends to speed up the process. Plus, bunnies love it, and with bunnies comes bunny poop. It’s one of the best fertilizers you’ll find. It’s a work in progress, but once it’s completed, I’ll have to mow like 2 times a season, I won’t have to worry about weeds, and it doesn’t need fertilizer. Clover is an incredible plant and I can’t wait until it’s completed.