There are weekly tournaments at Uncle's Games in Crossroads! You can get booster packs and (when available) promo cards. Here are the details from the store:
"Lend a hoof and solve the problems of Ponyville with your favorite mane characters!
$5 entry, swiss format tournament. Everyone gets at least one pack!
Tournament organizer: Ed Gayton"
Note: This meetup listing recurs monthly, however the event is weekly. Despite RSVPs being turned off, you will find a consistent group of both meetup and non-meetup players.