Eattini Thai in Ellicott City has lots of vegetarian options, and is one of my favorite restaurants in the area. I highly recommend their chive cakes appetizer.

Mango Grove is a really great Indian restaurant, has lots of both Vegetarian and Vegan choices.

Regionale has more limited options (just 3 vegetarian sandwiches), but they're all super tasty. I'm also in love with their house-made chips.