The acorn is the seed of the mighty oak tree; therefore, it symbolizes potential and strength, honour and longevity:
“The strongest oak of the forest is not the one that is protected from the storm and hidden from the sun. It's the one that stands in the open where it is compelled to struggle for existence against the winds and rains and the scorching sun.” Napoleon Hill
It is also a Nordic and Celtic symbol of life, fertility, and immortality.
The acorn as a heraldic symbol may indicate independence to its bearer.
Oak leaves also represent strength, stability or nobility.
When oak leaves and acorns are combined, the entire symbol can stand for power, authority or victory. For that reason, it is also commonly used on military tombs.
It is believed that the cross in which Jesus has been crucified was made of oak tree (although other kind of woods are also mentioned, such as wood from the cypress tree). It was a common practice to place children’s graves near oak trees.