Seven Shaped Clover is a trinket in Curiosity Crate, a mod for The Binding of Isaac.
+0.25 luck for each use of a slot machine, beggar, or shell game without gaining a reward.
Gaining a reward will reset the luck bonus and has a chance of granting a Lucky Penny depending on how high the luck bonus was.
Lucky Penny chance maxes out at 25% with a +7 luck bonus.