Simple Summary Knowledge of plants and their uses is an essential link between people and the environment. To foster biocultural diversity as a vehicle for mutually beneficial coexistence, we need to understand how plant-related knowledge circulates. Considering the rapid loss of biocultural diversity, especially in peripheral areas, the local dimensions of ecological knowledge circulation merit greater scholarly attention. Exploring the current Polish-Lithuanian-Belarusian borderland, we found relatively homogeneous wild food plant knowledge circulated within historically united, yet now separated, local communities of Lithuanians and Poles. However, we call for deeper qualitative analysis in order to detect recent changes in the flow of knowledge. The circulation of local ecological knowledge (LEK) is a promising avenue of research for wild plant studies. To encourage the acceptance, celebration, and appreciation of biocultural diversity, which is rapidly disappearing nowadays, we need to estimate and assess multifaceted local ecological knowledge. It has direct application for local communities in informing effective policies for improving food security and building community-specific responses to environmental and social transitions. The present study draws on data collected among two ethnic groups-Lithuanians and Poles-via 200 semi-structured in-depth interviews and participant observation conducted in 2018 and 2019 in Podlasie Voivodeship (Poland), the Vilnius Region (Lithuania), and the Hrodna Region (Belarus). We aimed to observe LEK circulation in the border area through cross-ethnic and cross-country comparisons. A total of 2812 detailed use reports of wild plants were recorded. In total, 72 wild plant taxa belonging to 33 plant families were used across the food domain. Our findings show that cross-country differences were minimal, while there was some variation between the ethnic groups selected as case studies. We emphasize the need, in future studies, to combine quantitative research with qualitative approaches in order to more thoroughly identify peculiarities of cross-border circulation as a reservoir for community food resilience and biocultural diversity.