It is shamrock, you know the irish clover where the leprachauns hide, but in Switzerland we have no leprachauns, just tons of shamrock. It grows everywhere in my garden, but this is the first time I managed to actually take a photo of the little yellow flowers. As soon as they flower, the flowers disappear. Thank goodness they are easy to remove from the garden; just a pull and the stems are removed with the roots, but that does not stop them returning. Every year the same battle with the shamrock and we are not even irish.