They look like coffee beans.

EDIT: sorry I didn't read the post carefully enough, to see that you had considered coffee beans and included one in the photo.

I guess coffee beans are more flat on the side with the furrow...

Here is a link that might be useful: Coffee beans on Google Images

This post was edited by mark4321 on Wed, Jul 9, 14 at 14:06

Here's a better guess. A palm of some sort. I suspect there are many species that look like this. I give a link to Canary Island Date Palm (Phoenix canariensis) below.

Here is a link that might be useful: {{gwi:244990}}

Thank you.

It really seems similar, including in the size.
I found dozens of these seeds in a small spot in my yard and I already found one palm tree about 100 m from here.
One of the seeds is already sprouting. Let's see what happens.

3 weeks later look how it is growing. Almost 4 in. (10 cm)

I found one of these seeds in my chook yard that is under a large Morton Bay Fig tree frequented by Chanel Bills. Just for the fun of it, I planted it in a pot and a week later I have a two inch tall palm of some sort---looking just like the above photo. Has anyone an idea of what palm it might be? I was very amused that it germinated---it must have been bursting to get out because it didn't waste any time.

Check if there are palm trees around and, if possible, post a photo.

They're either Sylvester date palm seeds, or Canary Island date palms.