This grower is sure of this plant identification.
Dug out as not happy in moist soil, will be split into more healthy clumps.
St John's wort, St Peter's wort
Hypericum genus (St John's wort). These are perennials and deciduous, semi-evergreen or evergreen sub-shrubs and shrubs. There are about 400 species. The flowers are showy and will bloom in shades of yellow. These are low-growing shrubs in mounded shapes; they will bear fragrant yellow flowers in the summer. Grow them in well drained soil with full sun.
Grown for their conspicuous, yellow flowers with prominent stamens. This shrub is very attractive to bees.