PIE FILLING is a type of food used to fill pies. Common pie fillings include MINCEMEAT (9 letters), RHUBARB (7 letters), MUD (3 letters), CUSTARD (7 letters), APPLE (5 letters) and WILDBLUEBERRIES (15 letters). Mincedmeat is a mixture of fruits, spices, suet and sometimes beef, while RHUBARB is a tart vegetable that is often cooked with sugar. MUD is a chocolate-based filling, CUSTARD is a creamy egg-based filling, APPLE is a sweet and tart fruit filling, and wildblueberries are a tart and sweet berry filling.