why are they wearing wheat in the house of commons

They are wearing wheat in the House of Commons to show support for "Back British Farming Day," an annual event organized by the National Farmers’ Union (NFU) to celebrate and raise awareness of British farming. MPs from all political parties wear badges or pins featuring heads of wheat to demonstrate their solidarity with British farmers and highlight the importance of local farming and food production to the UK economy. This tradition also coincides with parliamentary sessions like Prime Minister’s Questions, where politicians publicly display the symbol to promote British farming values and the contribution of the sector to the nation.