The first day of Lent is known as Ash Wednesday. Ashes are something that are left when something is burned. Christians use them as a symbol of being sorry for things they have done wrong and want to get rid of forever. In many Christian churches there are special services where the vicar or priest makes the shape of a cross with ash on the forehead of each person. The ashes come from last year's palm crosses which are burned and mixed with holy water.
Read about Mothering Sunday which is on the fourth Sunday of Lent.