Tempo will open up their resturant for a brunch and you can choose your own food or budget. They are super flexible- ask for Erin (owner).
Also in Newton Centre, Tartufo has a room upstairs that would be great for a small function of 25.
Lastly, I would not recommend the Tea place on Moody. The food is good but the ambiance is just - yuck. If you want to do a tea, check out the Tea Pot Room in Boxborough. I know is farther out that you wanted to go, but the food is incredible and the atmosphere is perfect for tea- very relaxing.