send sb sth
We sent Mom flowers for Mother's Day.
We sent her a letter of apology.

send sth to sb/sth
I'll send a copy to you.

These words mean "send" in some sense.

Turn sth in = phrasal verb [transitive] American English to give a piece of work to a teacher, your boss etc:
Have you all turned in your homework from last night?

Hand sth in phrasal verb [transitive] to give something to a person in authority:
Hand your papers in at the end of the exam.

send sth/sb in phrasal verb
1 to send something, usually by post, to a place where it can be dealt with:
I sent in a few job applications last week.

2 to send soldiers, police etc somewhere to deal with a difficult or dangerous situation:
British troops were sent in as part of the peace-keeping force.