Readings & Meanings:
to present a gift
What's a good Christmas present?
The books my grandfather left when he died were donated to the local elementary school.
貝 on the left. When Kai-hen is involved, think "valuable."
The part on the right derives from 曾. You can see this in 贈's previous incarnation:
曾 is a pictograph of a cooking stove with a steaming basket on the top, with wisps of steam piling up upon each other. The abstract idea is "pile up."
So, 貝 + 曾 = add more possessions to the ones you already have.
There's another おくる, with a similar meaning.
送る means to send (mail, wishes, people, anything).
贈る specifically means to give a present.