The Wallowa Mountains are the highest peaks in Oregon outside of the Cascade Range and are located in the extreme northeast corner of the state. You can take a tramway to the top or enjoy it from below at Wallowa Lake State Park, among many other things to do in the area!
A full guide on how you can plan to visit, things to do, where to stay, and where to eat is available from Never Stop Adventuring here: https://neverstopadventuring.com/2021/10/wallowa-mountains/