Do either of your parents work for a company that can hire you? My aunt officially hired me at her office, the summer after I turned 13. Which was the legal working age at the time. It was amazing to get that first check, and I actually saved most my stubs from that job. I mostly did filing and data entry on Saturdays. While she caught up on her work. Most bag boy jobs only require you to be 14 to work.
Do you have any kind of cooking skills? I used to make home made chocolate lollipops, using those plastic molds. Kids here and there at school would buy them from me.
One year in Middle school, I sold all my halloween candy. I don't like the "good stuff" like milk duds, almond joys, snickers, musketeers, and so forth. The day after, I brought some to share, but every one wanted some. So I started selling the better stuff for a quarter, and gum balls for five cents. I don't even know how much I made, other than the change weighed a ton.
And growing up, I used to always ask every one for pennies. Like my grandparents, and aunt, and mom. I hoarded pennies. Which turned into my first savings account with a minimum deposit of $50. $50 in pennies, weighs a ton. No one thinks much about pennies, but they can add up quickly.
In 9th grade, my aunt would give me $15 a week for school lunches. I think i spent like $2.75 or $2.50 so I had a little bit left over at the end of the week, including any days I skipped lunch. If you get a lunch allowance each week, take it to the grocery store and stretch it even further.
Try growing a vegetable garden in the spring and summer and see if your neighbors would want some. If anything, your mom might give you some extra money just so she doesn't have to buy it at the store.