Native seed predators, such as mice (Peromyscus spp.) and ground beetles (Carabidae), consume weed seeds and waste grain within agricultural fields and thus provide a potentially important service to farmers. Most previous investigations of agricultural seed predation services have focused on within-field factors that affect rates of seed removal and consumption by field-resident seed predators. However, seasonal migrants from adjacent non-crop habitats may also contribute to removal of weed seed, particularly along field edges. We investigated whether rates of weed seed removal within fields increased during summer crop growth when Peromyscus leucopus noveboracensis (White-Footed Mouse), a ubiquitous forest-dwelling rodent in the eastern US, seasonally migrates into crop fields from adjacent forested woodlots. We used exclosure experiments to quantify the relative number of Setaria faberi (Giant Foxtail) seeds removed from seed trays by vertebrate and invertebrate seed predators within 4 corn fields in central Indiana during 4 different stages of crop growth (emergence [May], vegetative [July], reproductive [August], post-harvest [November]). Seed-removal experiments were coupled with live trapping of rodents and pitfall sampling of invertebrates to identify seed predators. Vertebrates (mice) contributed nearly twice as much (∼50%) to seed removal compared to invertebrates (∼25%), irrespective of season. Rates of invertebrate consumption differed among seasons but were not affected by distance from forest—field edge. Rates of seed removal by mice significantly interacted with season and distance from field edge, with higher rates of seed loss near forest—field edges during July and August even though mouse abundance showed no strong association with distance. Increased seed loss near (within 90 m) forest—field edges was presumably due to consumption by seasonally field-resident White-footed Mice, which constituted the majority (>70%) of mouse captures near field edges. Peromyscus maniculatus bairdii (Prairie Deer Mouse) is a year-round resident in crop fields and most likely contributed to seed loss nearer field interiors, where they comprised >90% of the rodents caught. Although non-crop habitats are often overlooked as a source of seed predation services, our results indicate that forest-dwelling White-footed Mice likely supplement rates of in-field predation on weed seed. Future investigations of seed-predation services should consider the role of resident and seasonally opportunistic seed predators in regulation of weed populations in crop fields.