Had to google it, but yes, that's it - Wood Sorrel with the heart shaped leaves rather than the round leaves that clover has.Sheep sorrel,/clover sorrel?
Have you a snap of it ,
Or when would it appear ?
Again, I got this pic from google. If I remember correctly, it will be there all summer, but early summer ones tend to be sour whereas when they get into August, they are much tastier. The flavour was in the stem of them rather than in the leaves.