It depends. Most Oregon wineries welcome you to bring a lunch, and enjoy it while visiting with them in their tasting room. Some even have a specially designed patio with tables and benches for enjoying your lunch, while sipping their wine, and taking in the sweeping view of the surrounding vineyards.
If you’re not sure, call ahead and ask a member of the winery’s tasting room before you stop in for a visit. That way, you’ll be sure not to miss out on a perfect picnic location.