Solved Id please

The individual flowers on this are tiny, less than 1mm across.

 

Looks like Valeriana locusta syn Valerianella locusta...common name corn salad.

Corn Salad (Valeriana locusta) Identification -

Common Cornsalad | NatureSpot

File:Illustration Valerianella locusta0.jpg - Wikimedia Commons

Valerianella - Wikipedia

 

Thanks. Wonder where it has arrived from. Not something we have ever grown.

 

2 years ago a retired farmer who lives near me took me into the local Golf Course to id a plant he had never seen before.
As a farmer he knew his weeds, but had never come across this one...nor had I.
Out came my Wild flower books.
This week I discovered I now have several of the blinking things growing in my garden!

 

We have always known it as lambs lettuce. We do grow it but it does like to grow where we don't want it to grow. We eat the leaves before it flowers.

 

I was too idle to wade through the books looking for it. Sad person!