Common Field-speedwell
Veronica persica

© Bob Ford/Nature Portfolio     Common Field-speedwell photographed on March 1st 2008

Best seen at close quarters when the details of the tiny flowers become obvious. It was originally an Asian plant but was introduced 200 years ago and is now the commonest of all the speedwells. You almost certainly already have it growing in your lawn, which is a good reason not to use weedkillers as it's a lot more interesting than grass. The flowers can be seen through most of the year.