Beacon Strawberry Festival in Dutchess County
There's a pretty thorough review of the festival on the old tristate board:
IMHO, it's worth it if you decide to visit Dia: Beacon and the town (Poppy's Burgers, Zora Dora Paleteria, Crumb, etc.) as well as the festival. It's a great day trip if you decide to check out what else Beacon has to offer. You can also hit Cold Spring on the way up. It's a great little town. Unfortunately, the Hudson Valley Shakespeare Festival (http://www.hvshakespeare.org) starts next weekend. That experience is definitely worth the hour long trip. Hope this helps!