The unmistakable bright yellow of a rapeseed field.
This crop is a member of the cabbage family, Brassica napus. It gets its name from the Latin for turnip, rāpa. It is known as canola in North America. It is mostly grown for animal feed or biodiesel. In the past the oil from the plant was used for lamps or lubricating machinery. After soybean and palm oil, it is the third largest source of vegetable oil in the world. Pollination by insects increases yield and in turn it provides a source of nectar for bees and other pollinators. The pollen is associated with hayfever and asthma, but this could be due to the vast quantities grown.
In the above view you can see Hay Bluff (Welsh name, Penybegwn) part of the Black Mountains range in nearby Wales. This is it closer up.People like to jump off the top of it with paragliders.