Greenwood is by PG metro, but the wait list is EXTREMELY long (I think about 4 years) and it's pretty pricey. St. Ann's and Heritage (My DH is at Heritage) are right next to each other, in the Eastern Ave/Rhode Island Ave area.
Also, right there by St. Ann's/Heriage, there are a few church based daycares - Rheema, Our Redeemer, and I think about 2 more, but I can't remember their names. Also, there's Gateway Child Development Center in Mount Rainier, and Agape in Colmar Manner. There's also a home based daycare called Giant Steps on LaSalle Road in Hyattsville.