I'm 49 and I've been working continuously since I'm 15. Except for maybe one semester in college. Many times I had more than one job. My son will be 15 soon and he's in the same boat as you. Unfortunately, many places won't hire a kid 'til he's at least 16. For a regular job, you'll have to try locally owned places. My daughter got a job at Tropical Smoothie when she was 14. When I was a kid boys had paper routes and things like that. Those jobs don't exist any more. I have two pieces of advice for you;
If you do get a job at a local store or restaurant, show up on time, show up sober (hopefully that's not an issue), and don't steal. Oh, and it helps if you actually work while you're there. I know it sounds silly, but my oldest daughter managed a surf shop while she was in college, and she literally could not keep people employed becasue they couldn't follow those simple rules. She worked 60+ hours a week because people just didn't show up, or she had to fire them for being drunk or stealing. It was crazy.
My other suggestion is be a bit of an entrepreneur. It's been my experience that many, many people will not do even the simplest tasks for themselves. Put up signs in your neighborhood; shovel snow, rake leaves, mow grass, etc. You can make quite a bit of money like this; more than washing dishes or carrying groceries. The hard part is making sure you get paid enough. Sometimes it's hard to estimate how long a job will take when you give somebody a price. If people see that you work hard and do a good job, you'll have more work than you can handle.
Unfortunately, many kids your age just don't want to work. I live in a resort town, and the hotels have to import kids from eastern Europe to do the menial labor. Good luck!