I've just found these seeds in my terrace.
I have no idea what tree they came from. Could you help me? I'd love to plant them.
(Clue: I have a japanese maple in the terrace, but I think it's still too small to give seeds (it's not even 1 metre tall yet) and I think I would also have noticed.)
The certainly look like Japanese maple seeds.
If you are looking at your 1-metre tall tree from above, the seeds will be hidden under the leaves, and the flowers (which won't be there any more) are very inconspicuous.
If you want to plant them, they will not germinate unless they have a winter cold period.
If you just plant them in the ground, that will happen naturally if you have the right winter climate, and they will germinate next spring. Otherwise, you need to keep them in a refrigerator (but not in a freezer!) for 90 to 120 days before you plant them.
I agree with the other answer that they do look as if they might well be Japanese Acer seeds.
The only thing to add is that they do not often come true to the parent tree, so you won't know what tree you will get. You could grow on some seedlings and when they are big enough, try grafting part of your existing tree to them, then you will get more of the tree you've got, or just grow them on and see what they produce. Information on growing from seed and grafting onto seedlings here https://japanesemaplelovers.com/growing-japanese-maples-from-seed/
