if it helps, the leaves fold in half and close on the evening??
Is it a climber, bush or trailer?
Some sort of melon perhaps-when you say you found it in your suitcase where had you been?
it could have been from cyprus, maldives or florida. i'm really not sure!! i remember having it in my case for the last few years and then finally thought i'd grow it. all i know is what i've put and that the leaves fold down the middle and fully close every evening. the other thing is that it's a very strong/stiff sappling. the plant is at the moment only an inch tall. i've tried googling the picture to no avail. I keep trying to rack my brain of when i put it in my case.
the seed was larger than a penny and around the same thickness too
not a great picture, but this is it at night
It looks like Amicia zygomeris- Chrisopher Lloyd liked them apparently