Are all your dreams of the past night in your memory?

I am not sure how to title this topic. What I mean is: If you wake up do you have all the dreams you had somewhere in your memory only a few?

I ask this becouse this morning I woke up, dissapointed becouse I did not had any DR again. But then when I was going to school and I tought about the tests I rememberd I had a dream about it, just a flash/short dream. But only then I rememberd.

So basically, if I would find some triggers (for example a sheep If I had a dream about a farm with sheep) could I remember all the dreams I had that night, or do I only have acces to a few dreams I had?

(about the dream, I dream't I flunked 4 tests in school out of 8. I am not sure but maybe I remember saying: Oh well, let's see how I really did. As if I knew I was dreaming.
And I only screwed up 1 tests =) )

I think most linger somewhere in the depths, because you're right, they can be triggered throughout the day. But I also heard something about one dream cycle erasing the last dream from someone on here, I'm not sure on the specifics (or the validity) though.