Projectile point families, ground stone, and respect for living heritage.
North American lithics follow their own typologies: fluted Paleo points (Clovis, Folsom — with a channel flake up the face), notched and stemmed Archaic points, small late triangular arrow points, plus ground-stone axes with hafting grooves, bannerstones, and pipestone objects.
Point outlines and notch positions are the identification — regional guides are excellent. Beware modern knapping (a large, skilled hobby): fresh surfaces, uniform flaking, and unlikely materials mark replicas, and 'too perfect' collections often are.
These are the heritage of living nations: laws (including burial-protection statutes) and ethics restrict collecting on public and tribal lands, and human-associated objects deserve particular respect. Record state/county-level findspots privately, note material and typology, and when in doubt about an object's sensitivity, ask before cataloguing further.
Recognising Bronze Age metalwork
Recognising Iron Age and Celtic metalwork
Recognising Roman military fittings
Recognising Anglo-Saxon metalwork