First off, for the Moderators (Cal - you reading this?) - can we kick this one to the General small game, trapping, & predator hunting forum? This isn't a good topic to have in the reference sub-forum, as it's 1) most likely a troll, 2) a specific question which doesn't have broad appeal for future reference, and 3) Did I mention it's most likely a troll?...
If a guy could get a coyote close enough then to hold still long enough to kill it with a boomerang and a knife, I'd buy a ticket to that show!
I'm quite certain this is a troll post, but it's entertaining enough that I'll give it a few minutes of consideration. Food plots to attract prey animals to bring coyotes to your yard does not make sense. If you wanted to bait coyotes in your yard, then fine, but the "long con" of attracting mice and rabbits to your yard isn't going to reliably pay back. If you're in an urban area where you can't shoot, then a food plot isn't going to work.
Killing a coyote with a boomerang or a knife (I assume either thrown or stabbed after immobilized with the boomerang) is an incredibly unethical and equally dangerous mode of hunting. With a sharpened boomerang, you're talking about an incredibly inaccurate weapon, so there's no assurance of an ethical, quick kill. Being so close then to use a knife is far too close to be safe, and a scratch or bite by a coyote can lead to infection which might end your life.
All around, this is a terrible idea. If you have a coyote problem in an urban area, there are professional resources, typically free, available to help manage this issue. Second string to that would be trapping.
Boomerang and knife... SMFH...