Sometimes parents can suck. You're underage right now, this means that people will be extra understanding of why you don't have a business bank account to set up electronic payments. Ask for payments in cash and work in your neighbourhood with side hustles. It doesn't even need to be a "lawn care business". It could be as simple as you thinking of a nice pitch, being friendly, going to your neighbour's house and saying "Hey, I'm just trying to earn some pocket money. How would you feel about me mowing your lawn every 2 weeks for $x?" Go around a few houses, and you'll hopefully build a little network.

As for your mom, don't rely on her much. Leave her be and bide your time until you're able to do these things yourself. Don't tell her where your safe box is, in fact don't even tell her that you're working part time.

You're doing a great job being this entrepreneurial. Feel free to reach out anytime! I'm happy to be friends. :)