Are these sentences phrases, independent clauses, dependent clauses or none ?It seemed that everything old is new again. There were dresses in...

"That everything old is new again" is a dependent clause. A clause has a subject and a verb. (Everything old = subject, is = verb) To make a clause dependent, it must feel like it needs something more to complete the thought. The word that performs that function. Other words that could have introduced this dependent clause could have been which, what, whatever, who, whoever, when, because or since... just to name a few.

"in store windows" is a prepositional phrase. It begins with a preposition and ends with its object.

"that they'd worn it all before" is a dependent clause... once again, if it was without the word "that" it would be independent.

The last one is independent because it can stand completely on it's own without other phrases or clauses to make it's own complete thought.