Drift seeds and found seeds: share what you found, get id help, try to sprout

If I find a seed, I pick it up. If it seems viable, I put it in my pocket.

I find a lot of seeds at the beach. Many seeds are dispersed by ocean currents, called drift seeds. The most famous probably being the coconut, which I did find one the other day! I've been told, if you can still hear the coconut water sloshing around inside when you shake it, it's still viable. So, although it's a bit too cold here for coconuts, I'm gonna try and sprout it.

But not everyone lives by the beach. No problem! I find lots of seeds in the street; of course watch out for cars. Many seeds are dispersed by wind, animals, or just rolling down the hill.
A lot of times I find a seed I haven't seen before. It's hard to find resources for identifying just seeds. If I can sprout it, the leaves sometimes narrow it down.

So if you find a seed out of place, post it here. If you get it to sprout, let us know how you did it.
**as always, check on the possibility of invasiveness before introducing an unknown plant to your land**

A thread where I sprout walnuts found on the beach:https://permies.com/t/128105/Walnuts-washed-beach-sprout-find
A thread where I sprout air potatoes from the beach: https://permies.com/t/142973/Air-potatoes-Dioscorea-spp-washed


I need help figuring what the seeds in the third picture are???
It seems like the kind of plant that if you were familiar with it, you would know it right away. Picking away the hull reveals the hard seed in the left of the picture. These are all over the beach, southern kansai coast. It's possible they drifted here or were washed down a river and back onto the beach.