The search for suitable materials of environmental and wild food origin to be transferred into reference materials with low and yet elevated levels of radioactivity is described. Wild berries are selected as candidate reference material and the processing of this material into powder form is described as well as the homogeneity study of the whole processed batch. In a global perspective, the dominating radioactive contamination source is global fallout of debris from the atmospheric nuclear bimb tests conducted in different parts of the world between 1945 and 1980.