I once asked my mom if my grandmother (her mother in law) was rich. Her reply: “No, but she likes to think she is.” I think she meant my grandmother spent money like she had plenty of it when she really did not. Can relate. I hope you do better!
There’s always a temptation to throw money at your problem. But remember there’s nothing you can buy that will make up for what is really needed. And the stuff that accumulates while you try to fix the problem just ends up being a problem on its own.
Have them sort change, and eventually to count it. It teaches them to gather things that are alike, it's an introduction to money and it occupies them for 15 minutes! Just make sure they're old enough to be past the point of putting coins in their mouth.
Have a yearly “review” right before school year. Raise allowance as appropriate. If they want more money, they’ll have to take on more responsibilities.