Okay, so I didn't really forget how to say it... I just wanted a clever question title.
In my Spanish class I was taught that olvidarse is reflexive:
Me olvidé (de la cita).
Me olvidé (las llaves).
Google translate agrees with this translation.
Tonight, a friend of mine (a native Mexican Spanish speaker) told me that sounded awkward, and suggested simply:
Olvidé (de la cita).
Olvidé (las llaves).
But also suggested that a more correct way of saying I forgot is:
Se me olvidó (de la cita).
Se me olvidaron (las llaves).
Along with the similar forms:
Se me han olvidado... → I have forgotten...
No se te olvide... → (You) Don't forget...
Are all of these forms considered "correct"? Is there a preferred form for "I forgot" or "I have forgotten"?
Please note that my question is about the verb form to use (reflexive, versus non-reflexive, versus passive). I hope the rest of my sample questions are correct, but if they are not, please edit them to be grammatically correct.