Habitat - urban
No interactions present.
This is the double form Kerria japonica 'Pleniflora'.
David J Trevan
.. and so much prettier than the species.
They can be very invasive, as they send suckers up for yards around, but this could be a seedling (which is a little unusual for 'pleniflora') as it appears to be rooting at the join of a path and a wall.
Unless there is a large specimen of it, on the far side of the wall, and it's merely suckering underneath.
How to take close-ups with cheap phone and hand-lens:
Field Guides for Budding Botanists:
I did try to check whether this plant came from a shoot or a seedling, but I couldn't see through or over the wall to tell whether it had grown up from a plant on the other side.
... so the default hypothesis would be a sucker.
....as Stuart says, it's usually suckers, and as I mentioned, this form - the expensive, desirable, cultivated one - doesn't usually set seed, being normally propagated by cuttings.
So if you like it, but not there, take some cuttings, then spray it with glyphosate-based weedkiller; if it is a sucker, you won't get it out by digging or pulling.
Lat/Lng: 51.6209, -0.0006
OS grid ref: TQ385932