Birthday gift for a friend I've known for 6 months?

I met Sarah through a hiking group about 6 months ago, and we've become pretty good friends. We hang out maybe once a week - hiking, grabbing coffee, or just chatting. Her birthday is coming up, and I want to get her something nice but not too intense since we haven't known each other super long. My budget is around $25-50. She's really into fitness and outdoor activities, loves her coffee (always has a travel mug), and mentioned she's trying to be more environmentally conscious lately. She has a good sense of humor and is pretty practical. What kind of gift hits that sweet spot of thoughtful but not overwhelming for a 6-month friendship? I don't want to come across as too eager, but I do want to show I care about our friendship.

Thanks for any ideas!