Sounds similar to York Castle Ice Cream, which has a storefront in Silver Spring, but also distributes to many vendors throughout the Washington area. And yes, they have grape nut, guiness, lucuma, many tropical flavors- my favorite being the mango. Thank goodness there is no mauby.
Thanks for the heads up. BTW, it's in MT. RAINIER (not College Park, though it's not far from College Park). Can you edit your heading? It is actually on my daily commute home to College Park (OK, 1/2 a block off) so I will definately stop in.