Can you name these wildflowers?

In my earlier posts about my wildflower meadow walk I posted my pictures of buttercups, daisies, dandelion clocks and the may tree. I took pictures of other plants that I don’t know the names of. If you recognise any of them perhaps you could help me out by telling me in a comment to this post.

Picture 1. A drift of tiny blue flowers.
Picture 2. A closer view of the tiny blue flowers.
Picture 3. As kids we used to call this milk maids knee.

Picture 4. Tiny blue flowers on a nettle.