Traditionally, mobile media sharing and messaging has been studied from the perspective of an individual author making media available to other users. With the aim of supporting spectator groups at large-scale events, we developed a messaging application for camera phones with the idea of collectively created albums called Media Stories. The field trial at a rally competition pointed out the collective and participative practices involved in the creation and sense-making of media, challenging the view of individual authorship. Members contributed actively to producing chains of messages in Media Stories, with more than half of the members as authors on average in each story. Observations indicate the centrality of collocated viewing and creation in the use of media. Design implications include providing a ""common space"" and possibilities of creating collective objects, adding features that enrich collocated collective use, and supporting the active construction of awareness and social presence through the created media.