Alien!!

Between walks on Saturday I spotted this growing in the garden. It looks very alien but is an everyday plant often found in gardens in Britain and Sweden and probably all over the world. In a couple of months we'll be eating it! This is a macro shot - the plant was about 2,5 cm across.
Any ideas?
The walks - 7 km with Jan, followed by a pause, then 7,5 kms on my own. The regime seems to be working as a month back 7 km left me totally *******ed.