Biological collections contain a rich and diverse history of life on the planet. While collections are typically made to voucher the occurrence of species in a specific time and place, the wealth of data captured within a collection can extend well beyond their original intent and help to resolve modern scientific problems. For example, historical collections can add depth and time points to population genetic analyses and incidentally co-preserved fungi and insects can be used to inform biological control efforts. Here we highlight some non-traditional use of collections of rust fungi (Pucciniales) that were used to: 1) reconstruct the historical emergence of one of the world’s most important phytopathological diseases, coffee leaf rust, as well as determine the means by which it is spreading; 2) discover new species of potential rust biological control agents; and 3) examine suitability of rust mycoparasites (e.g, Spherellopsis spp.) and pests (Mycodiplosis spp.) for biological control. Because Pucciniales are non-culturable organisms, the wealth of material within biological collections remains one of the best resources for studies of these fungi.