Veronica speedwell

Whilst cutting the grass I noticed hundreds of these little blue flowers.

Slender speedwell (Veronica filiformis) is a low-growing plant with bright blue, long-stemmed flowers early in the year, usually March to May. It is low-growing and can form dense patches in a lawn. It was introduced to Britain from Turkey and the Caucasus during the early 19th century. It was much grown as a rock plant until gardeners realised how invasive it could be. It is now widely naturalised in many parts of the country and is a common and troublesome lawn weed.