Institutional food is renowned for being monotonous and unappetising, yet the accuracy of these prescribed diets is difficult to verify archaeologically. Desiccated plant remains from beneath the floorboards at Hyde Park Barracks in Sydney offer a rare insight into the culture of food at the Female Immigration Depot (1848–1887) and the Destitute Asylum (1862–1886). Here, the author reveals the wide range of unofficial plant foods accessed by inhabitants at these two institutions—representing resources sourced from across the British Empire—and the sometimes-illicit nature of their consumption, highlighting the importance of incorporating archaeological evidence into discussions of institutional life.