The Feria del Agricultor runs every Friday morning on the street just off the central park, and it is the best reason to time your visit to coincide with the day. Farmers from the surrounding hills bring fruit, vegetables, cheese, fresh bread, and prepared food. The produce is notably good — Atenas sits in prime growing country for citrus, avocado, and plantain, and prices are a fraction of what you'd pay in San José supermarkets.
Arrive before 10am for the best selection; it winds down by midday. Bring a bag and small bills. The tamales and fresh-squeezed juice stalls near the entrance are worth the visit on their own.