Between the bricks

So when I took the dogs for a walk at the farm I noticed this interesting plant growing between the bricks. There are many of them and they are quite tiny. I have no idea what type of plant life it is though.
B and I have been to
Visit B’s cats. Bertie was there to greet us but Mitsy was more difficult to find. I looked in the woods and then just as I was looking up a tree wondering if she was hiding there she came dashing across the road to me so all was well in the end!