Background: Interactions between societies and nature are regulated by complex systems of beliefs, symbolism, customs, and worldviews (kosmos), ecological knowledge (corpus), and management strategies and practices (praxis), which are constructed as product of experiences and communication of people throughout time. These aspects influence social relations, life strategies, and cultural identity, and all of them in turn influence and are influenced by local and regional patterns of interchange. In this study, we analyze the interchange of wild and weedy plants and mushrooms in traditional markets of the Phurépecha region of Mexico. Particularly, the social relations constructed around the interchange of these products; how knowledge, cultural values, and ecological factors influence and are influenced by interchange; and how all these factors influence the type and intensity of biotic resources management. Methods: We studied three main traditional markets of the Phurépecha region of Michoacán, Mexico, through 140 visits to markets and 60 semi-structured interviews to sellers of wild and weedy plants and mushrooms. In nearly 2 years, we carried out 80 visits and 30 interviews in the "Barter Market", 20 visits and 15 interviews in the "Phurépecha Tiánguis", and 40 visits and 15 interviews to the "Municipal Market". We documented information about the spaces of interchange that form the markets, the types of interchange occurring there, the cultural and economic values of the resources studied, the environmental units that are sources of such resources, the activities associated to resources harvesting and, particularly, the management techniques practiced to ensure or increase their availability. We analyzed the relations between the amounts of products interchanged, considered as pressures on the resources; the perception of their abundance or scarcity, considered as the magnitude of risk in relation to the pressures referred to; and the management types as response to pressures and risk. Results: We recorded 38 species of wild and weedy plants and 15 mushroom species interchanged in the markets. We characterized the spaces of interchange, the interchange types, and social relations among numerous Phurépecha communities which maintain the main features of pre-Columbian markets. The products analyzed are differentially valued according to their role in people's life, particularly food, medicine, rituals, and ornamental purposes. The highest cultural values were identified in multi-purpose plant and mushroom resources and, outstandingly, in ornamental and ritual plants. In markets, women are the main actors and connectors of the regional households' activities of use and management of local resources and ecosystems. The interrelationships between worldviews, knowledge, and practices are visible through the interchange of the products analyzed, including the types of environments comprised in communitarian territories, agricultural calendars, and feasts. Those plants and mushrooms are highly valued but relatively scarce according to the demand on them receiving special attention and management practices directed to ensure or increase their availability. With the exception of most mushrooms and ornamental and ritual plants, which have high economic and cultural values, there are those that are relatively scarce and under high risk, but are obtained through simple gathering from the wild. Conclusions: Traditional markets are crucial part of the subsistence strategy of Phurépecha people based on the multiple use of resources and ecosystems at the local and regional levels. The markets influence social relations, cultural identity, and preservation of traditional knowledge and biodiversity. In general, the demand of products in markets enhances innovation and practices for ensuring or increasing their availability, particularly those that are naturally scarce. However, it was notorious that, althoug mushrooms and ritual plants have high demand and value in markets, most of them are obtained by simple gathering. [ABSTRACT FROM AUTHOR]