Elevate Elite has young girl teams. Potomac Valley Thunder may also have a 2nd grade team - I don’t recall.
I would also check out Arlington Hurricanes, although their em teams are not as good from our experience.
Basketball really kicks off around 5th grade, but some girls get into it early.
For example, the Fairfax Stars is the top club in our area, but their youngest team starts at 4th grade. If your DD is good enough, the Stars occasionally let young players play up. Email the 4th grade coach and have your DD attend a practice to see if she is good enough. You’ll know pretty quick if she can play at that level.