A group of residents is opposing a solar farm proposed for an East Street cornfield. The newly formed East Street Neighborhood Association gave selectmen a petition with 100 signatures protesting the solar panels proposed by Boston-based Citizens Energy, a nonprofit founded by Joseph P. Kennedy II. The petition cites concerns about the project’s impact on property values and ground-water quality. State law prohibits towns from rejecting solar farms, but towns may stop projects deemed to threaten the welfare of the community. The Planning Board is scheduled to discuss water protection on the proposed site on March 20, and a zoning board hearing on the matter is scheduled for March 26.