?Sycamore tree seedlings. Certainly looks like an Acer seedling of some description.

I agree with Sycamore … used to get loads.

It looks like a Sycamore. The two narrow 'leaves' are seed leaves (cotyledons) and are present inside the seed. They emerge from it after the seed germinates. They contain nourishment for the developing plant until it forms roots.

If you have Sycamore trees in the vicinity it's probably come from them, wind blows the seeds around.

yes it is sycamore. I have hundreds and the nearest tree is 2 streets away. their seeds are the whirly birds or helicopter seeds that we used to play with as children.

Thank you :)