One of my favourite sites in the spring English countryside is wild violets (aka English or sweet violets, viola odorata). For a few short weeks the whites, purples and pinks pop up above dense mounds of rough, glossy leaves under hedges and along streams.
An excellent early food source for bees and a lovely plant for a shade or woodland garden or for underplanting. We have them under our roses and cordon apples and pears and they quickly colonised a patch of bear earth left when we lifted the crown of a very large holly.
The seeds blow in on the wind so are scatter around the garden. They are are shorter than the grass and are never planned, popping up in the oddest places, but they are so lovely I leave them be and let them colonise and am rewarded for my laziness every spring.