Agriculture underpins rural livelihoods in Cambodia, where roughly 1.85 million holdings across 3.2 million hectares are overwhelmingly smallholder, averaging 1.7 hectares each. On plots of this size, field scouting is still performed on foot: the method is slow, physically demanding, and epistemically limited, as the observer sees the crop from within the canopy and localised pest, weed, or irrigation problems are noticed only once they grow conspicuous from ground level. A second gap concerns memory, as the location of an outbreak is retained informally and is generally unrecoverable on a return visit. Commercial agricultural unmanned aerial vehicles (UAVs) address both limitations but are priced for enterprise-scale operations and cannot be justified across a 1.7-hectare holding. This paper presents AgriMap, a low-cost aerial field-monitoring platform pairing an open-hardware F450 quadcopter with an automated routine that triggers the camera every five seconds, stamping each frame with latitude, longitude, altitude, and battery state. Frames are stored in a Laravel and MySQL backend and rendered as interactive Leaflet markers over a field basemap, producing a persistent, searchable inspection record. Mission logic and operator workflow were validated in a Unity simulation prior to deployment. The system was assembled for USD 256.70, and all hardware specifications and dashboard source code are released openly.