Went here for afternoon tea. $18 for tea service including tea sandwiches (chicken salad, egg salad), scones (peanut butter, cinnamon), and petit fours. For $7 extra you can add on a glass of champagne or wine, for royal tea.
Slightly pricey, but it's expected for a museum café, and the tea service is worth it for the experience. Make sure you make reservations on the weekends, because it's a small space. Their outdoor seating has a relaxing atmosphere, perfect for summer Sunday afternoons.
Even you aren't in the area for the museum or the park, it's still worth going out of your way for the brunch prix fixe or the afternoon tea experience.