Many mushrooms contain powerful compounds that boost immunity, such as shiitake, maitake, reishi, cordyceps, and turkey tail. Records of the medicinal use of turkey tail (Trametes versicolor) date back to at least the 15th century in China, and a recent clinical study has shown that it can augment conventional therapies for breast cancer by increasing immune-fighting white blood cells: http://www.huffingtonpost.com/paul-stamets/mushrooms-cancer_b_1560691.html

Turkey tail is an abundant mushroom found growing on dead trees, logs, branches, and stumps worldwide. More medicine from nature!