Senior citizen needs help with grooming and maintaining yard and garden; weeding, removing invasive vines, thinning crowded flower beds, mulching, etc. This would be ideal part-time work for an able-bodied person who loves gardening/yard work, and would like to earn some extra cash doing it.
Work can be scheduled to suit your needs. Save up for college, save for a rainy day, supplement your family's income, you name it.