You can find a farm that offers strawberry picking by checking with your state's strawberry growers' association or checking with local farms. Pickyourown.org has an email service that will notify you when strawberries are available for picking in your area. Some farms offer these services as well. Local newspapers also highlight local strawberry farms that offer picking.
U-Pick farms usually maintain a schedule of what crops are available for picking. Strawberries are in season from late May through June, though farmers recommend contacting the farm before the earliest date because strawberry availability varies on location, weather conditions, and varieties planted. Strawberries come into season sooner in the southern United States than they do in the northern U.S. They can come into season as early as April in Florida and Texas, May in the Deep South and later June in the Far North and Canada.
Your chosen farm can provide information on what to bring, farm rules, and products and services offered. For example, Linville Orchards in Pennsylvania provides their crop schedule, the day's weather, and tip on what to bring for the day. Their crop schedule indicates that they grow a variety of strawberry called the Everbearing that is available into mid-October.