I just want to know what causes them. Is it a certain food or drink...and how can you remeber then---if you can. do certain foods cause certain dreams?

Unresolved stimuli is the short answer - be that in the form of continued nagging fears, joys, unresolved business of some sort - or indeed, some sort of disagreeable food, fatigue or starkly shaking imagery of some sort such as horror movies, etc.

Any and all of these can contrive to start a dream - and the brain pulls material from a wealthy hidden cave of treasure by which to splash up the images and stories we 'see, hear, feel, smell, touch and taste' in them. A marvelous organ, the brain. Dreams are the synthesis of things logical, illogical and even magical created by that mysterious organ.

Remember dreams? Few people can remember more than a fraction of the dreams they truly have - nor sense that most dreams last little longer than a few moments, even when they seem to represent hours of life.

Certain foods do cause dreams - in essence, those which disagree in a certain way. This happens most profoundly when meals or snacks of such things are taken late - too close to sleeping time.

I hope this is helpful in answering you question - none can know the fully answer, but these are some thoughts from much human observation of that fleeting spirit, the human dream.

All the best to you.

Foods that cause digestive issues for you can cause bad dreams. If you want to remember your dreams, the vitamin B6 has been (anecdotally, though not scientifically) shown to help with remembering them. However, I think the most effective thing is to keep a dream journal. Every morning right when you wake up write down everything that you remember from dreams, no matter how trivial. This works for lots of people, probably because it gets you in the habit of transferring subconscious thoughts to your conscious mind.
Also, some people find that sleeping positions influence their dreams. I've never noticed this in myself, but you might want to experiment with it.