White Flowers

Burnet Saxifrage (Pimpinella saxifraga)
This plant’s open flat-headed flower structure supplies an abundant supply of easily accessible nectar and pollen which is essential for foraging bees to sustain their colonies and feed their brood.  It is listed on the RHS’s “Plants for Pollinators” list  and its late-season flowering (typically June to October) supports bees during transitional periods when many other flowers have faded. Its tiny star-shaped creamy-white flowers are grouped in airy clusters (umbels) and this flat landing platform accommodates all types of bees - from heavy bumblebees to smaller solitary bees - allowing them to land safely and easily reach the nectar.
 

Dropwort (Filipendula vulgaris)

Dropwort’s beautiful nectar-rich flowers attract a wide array of foraging insects, including bees, butterflies and hoverflies during the summer months. Its finely dissected, fern-like foliage grows in tight tufts alongside native grasses creating a micro-habitat and hiding spot for ground dwelling beetles and spiders.

Enchanter’s Nightshade (Circaea species)
The tiny pinkish-white flowers provide nectar and pollen for small bees (like sweat bees) hoverflies and bee flies and the leaves serve as a food source for caterpillars of various moths, including the striking Elephant Hawk Moth.
Fairy Flax (Linium catharticum)
Fairy flax white flowers bloom from May to September.  They are small and delicate in appearance but very attractive to pollinators as they are a rich source of nectar.
Field Bindweed (Convolvulus arvensis)
The nectar of the trumpet shaped flowers is popular with pollinators and its leaves are the food source for a number of moths including the White Plume Moth and  the Convolvulus Hawk Moth. The Four-Spotted Moth larvae specifically target Field Bindweed preferring its buds and flowers.
Hoary Plantain (Plantago media)
The leaves serve as essential caterpillar food for several butterfly species, most notably the Meadow Brown and Small Skipper. The flowers, which bloom from May to August, provide large amounts of accessible pollen for bees, hoverflies and beetles.

Lady’s Bedstraw (Gallium verum)
Its frothy yellow or white flowers are the primary food plant for caterpillars of several striking UK moth species, including the Hummingbird Hawkmoth, Small Elephant Hawkmoth and various Carpet moths (e.g., Red twin-spotted, Common and Wood Carpets).
The honey-scented flowers are a magnet for bumblebees, honeybees and day-flying butterflies. 
Mouse-ear - Common (Cerastium fontanum)
Its tiny white flowers are a nectar source for bees and various flies. They are especially important for early season support, blooming before many other flowers appear. It serves as a primary food source for the caterpillars of the Small Yellow  Underwing and Coast Dart moths. 

Ox-eye daisy (Leucanthemum vulgare)

Studies have shown that Oxeye Daisies are among the top-ranked pollen producers in wildflower meadows, providing massive energy reserves for short-tongued bumblebees and solitary bees. Their flat, wide flower heads make pollen easily accessible to a wide variety of insects. Certain species, like the Patchwork Leafcutter bee, specifically visit the Oxeye Daisy to harvest pieces of the white petals to line and build their nests. After the long blooming season, the spent flowers form seeds that are eagerly eaten by small mammals and seed-eating birds.

Sneezewort (Achillea ptarmigan)
Its flat white flowerheads and long blooming season make its pollen and nectar an excellent food source for various insects, including the metallic green Tansy beetle and the rare Small Streaked Case-bearer moth. Sneezewort is on the RHS Plants for Pollinators list.
Soapwort (Saponaria officinalis)
The long-tubed pink or white flowers are highly fragrant (especially in the evening) and are prized for their nectar. They draw in bumblebees, hoverflies, butterflies and night-flying insects like Sphinx and Owlet moths. The plant acts as a key host for Hummingbird and various other moth caterpillars.

Squinancywort (Asperula cyanchica)

The fragrant star-shaped white flowers bloom from June till September providing a crucial source of nectar for bees and butterflies during the peak summer months. Being closely related to bedstraws, it acts as a food plant for specialised micromoths and specialist beetles (such as the Bloody-nosed beetle (timarcha tenebricosa). Squinancywort has faced significant declines due to agricultural changes making its preservation important for the wider ecosystem.

Thyme-leaf Sandwort (Arenaria serpyllifolia)
Its tiny white flowers bloom from June to August providing an early to mid-summer nectar source for native bees, beetles and syrphid flies. The plant produces small seed capsules which serve as a valuable food source for small seed-eating birds such as finches and sparrows.

Valerian (Valeriana officinalis)
A valuable plant as its fragrant nectar-rich flowers attract pollinators like bees and butterflies and its dense growth provides shelter for small wildlife and invertebrates.
White Clover (Trifolium repens)
Widely recognised as one of the best plants for pollinators, White Clover blooms from May through October providing a long-lasting, reliable source of nectar and pollen for domesticated honeybees and various bumblebees. Its leaves serve as a key food plant for caterpillars, such as those of the Common Blue  butterfly.
White Stonecrop (Sedum album)
The star-shaped white flowers are rich in nectar and have a simple structure, making them highly accessible to short-tongued insects like hoverflies and various beetles as well as bumblebees. Blooming heavily throughout the Summer (typically June to August), it serves as a reliable, continuous lifeline when other nectar sources may be scarce. The hunkered-down mat-forming growth habit creates a cool, damp micro-climate underneath its stems. This provides essential daytime cover for ground-dwelling insects and small foraging animals.

Wild Carrot (Caucus carota)
Wild Carrot is an important larval food plant for several moths, including the Sussex Emerald (a highly localised and rare UK Biodiversity Action Plan species, whose caterpillars feed exclusively on this plant), Lace Border, Dotted Border, Chalk-carpet and Straw Dot.  Adult butterflies, such as the Swallowtail, Brimstone, Red Admiral and various Skipper species, use its flat frothy flower heads  as an essential nectar source. The nectar sits on an open flat-topped flower cluster making it highly accessible for both honeybees and solitary bees.  

Wild Strawberry (Fragaria vesca)
The white flowers of the Wild Strawberry plant, blooming from April to July, provide a crucial early source of nectar and pollen for bees, hoverflies, butterflies, moths and beetles. It is the larval host plant for various butterfly and moth caterpillars including the Grizzled Skipper and the Strawberry Tortrix moth.
Yarrow (Achillea millefolium)
Pink or White flowers. Because it blooms across an exceptionally long season, from early Summer till late Autumn and supports over a hundred different insect species it is an immensely valuable food source. Its flat- topped flower clusters act as an accessible landing platform and so are highly attractive to short- tongued insects that struggle with deep flowers, such as hoverflies, solitary bees and beetles. The feathery leaves are a primary food source for the larvae of various lepidoptera including the Large Skipper butterfly and the Belted  Beauty moth. Yarrow is famously favoured by ladybirds, lacewings and predatory wasps. These insects feed on the pollen and nectar before hunting common garden pests like aphids.