I drove my car slowly over my neighbor's flowerbed
That sounds careless to me. Why would you do something like that ?
I don't care about my neighbor's flowers anyway.
It's wrong to operate your vehicle carelessly and damage other people's property. If you damage something you prevent another person from being to use or enjoy it. You should try to make amends with your neighbor by paying him or her for the damage that you have caused through your reckless driving.
I want to pay for it but I don't have enough cash.
You should have thought about it before destroying your neighbor's flowerbed. Take a loan or borrow money but make some arrangement to compensate their loss.