Green olives are actually very immature when harvested anyway, and the seeds will definitely not grow. Olives are a dark purple black when ripe, but you can seldom find them in any stores where they have still viable seeds in them. Standard 'exotic' seeds to plant are avocado, mango, all citrus fruits, and kiwi (Makes a vine). A nice one is sun-dried dates. Your coffee beans are probably roasted and thus killed, but coffee is a toughie anyway.

Thanks, I think I'll try Kiwi, mango and date. Do you have to scarify the mango and date since they have such hard seeds?

It's fairly easy to find ripe olives that have not been pitted. However, you are correct in assuming that the seed has been killed by the brining.

Since you mention that your coffee beans came from a conservatory, I assume that they were NOT roasted! As long as they have been allowed to mature on the plant, and then planted fairly soon after harvesting, I believe that they will germinate.

But does the coffee bean have to dry out? I took green ones from the tree and brown ones. I planted the green ones but the brown ones have dried out.

The green ones are not mature. Coffee fruit is red when it is ripe. I've attached a link to just one of many articles on growing germinating coffee beans.

Cut and paste this link to see pictures of the coffee fruit (in which the two 'beans' are hiding).
http://www.therealcoffeeco.com/treebeansred.jpg

Here is a link that might be useful: Click here for information