1. I'm looking for a present "for my daughter's birthday."

(Is 'for my son's birthday' an adjective phrase or an adverbial phrase? What does it modify?)

2. I got a nice gift "for my birthday."
(Is 'for my birthday" an adjective phrase or an adverbial phrase? One says it's an adjective phrase. The other says it's an adverbial phrase. Does it modify 'got' or 'gift'?)