Honey bees are brilliant pollinators

Honey bees are the most efficient of insect pollinators as they don't wander from flower to flower in the way a Bumble bee does - instead they target a single plant source like your garden's sedums, and continue to work it until all the nectar and pollen on offer from the shrub has been taken. It means the honey bees are rubbing the flower's pollen on their bodies and then across the same type of flower, rather than buzzing off to visit another plant leaving your sedum gasping for pollination!

Nectar is offered as a 'thank you'

Plants produce nectar to lure pollinating insects to visit them, in the hope that while feeding the bees, moths, beetles, wasps etc will get covered in pollen which they'll take to the next flower they visit and leave stuck to the plant's stamens - their reproductive organs that need to be fertilised if they're to fruit and go to seed.

Flowers and bees have a 'language'

There are all sorts of signals that the flowers give to insects to tell them that they have nectar: some change colour when they're fertilised, or give off a small electric pulse that changes when they  flower is out of nectar. The plants are all working with the insects to make pollination as efficient and successful as possible.

Look at the white candle flowers on the horse chestnut and you’ll see some turn pinky red. In the same way, a forget-me-not flower gets a pinky red centre and white clover a pink blush to it once it’s been fertilised. A clear sign to pollinators not to bother with that flower anymore and look elsewhere.