word choice - Another example where I don't know if 欲しい or 欲しがる is right

私の祖母は私が欲しい以上のものをくれた

私の祖母は私が欲しがる以上のものをくれた

I want the meaning to be "my grandmother gave me more then I wanted." Is the second sentence right and the first sentence wrong?

I learned 欲しがる for the third person, but I found the second example as a first person example. Which is correct?

Answer

The generalization that がる is used only for third person is wrong. Both of your examples are grammatical, but only the first one means what you want.

私の祖母は私が欲しい以上のものをくれた
'My grandmother gave me more than what I wanted.'

私の祖母は私が欲しがる以上のものをくれた
'My grandmother gave me more than what I expressed that I wanted.'