Child labor laws limit the types of work teenagers are allowed to do, but that shouldn't be a big issue. You can see the restrictions at http://www.stopchildlabor.org/USchildlabor/fact1.htm
Golf courses hire teens for caddy jobs. These tend to be excellent jobs.
Yard work, as other self employed work such as house cleaning, pet walking, baby sitting, running errands, etc. is definitely not pointless. For numerous reasons it's just harder to get a business up and going than getting a fast food job.
Good jobs for teens without experience include fast food, restaurants, grocery stores, movie theaters, libraries, restaurants, retail stores, landscaping/lawn service, hardware stores, temp agencies, etc. Every store in the malls and strip malls near your house is a potential employer.
You will need a work permit from your school, which you can get from the office. You should also ask if the school has a work-study program. This is a program where local business sign up with the school to hire students.
Also check out job listings on your local craigslist http://.craigslist.org/.