A simple magic system for "cunning folk" type casters. I've used it as a feature of bucolic Halflings and in pseudo-historical settings.
These little spells (rhyming verbal incantations) either replicate a low-level Cleric or Magic-User spell or achieve a small desired effect (Referee’s discretion).
Cleric spells: Bless, Command, Cure Light Wounds, Protection from Evil, Purify Food & Drink, Remove Fear, Sanctuary, Delay Poison, Heroism, Resist Cold
Magic-User spells: Faerie Fire, Feather Fall, Light, Mending, Unseen Servant
The maximum number of attempts (successful or failed) each day is equal to the character’s level (or one, in the case of unlevelled NPCs). The chance of success increases as the character progresses in level:
Level Chance of success
9+ automatic success
Spells can be cast as a group effort. Each member of the group must be of the cunning folk. Add up the levels of all participants (treat level-0 as a "half" for this purpose), and use the total to define the chance of success.
An attempt can also be expanded to gain “advantage” on an attack roll or a saving throw (roll 2d20 and take the higher result). This works automatically, but has to be declared before the roll is made.