they look like trade beads but not the period the chevron bead is from....but i would asume if you found a chevron bead then yes...they r trade beads...never seen anything like the red triangle one....not 3 dimensional .....just flat triangular beads made of catlinite(minnesota pipestone) or local red slate...nice finds!...definatly different type of beads...it would not be unusual though...all kinds of different things can be found on sites
if they r indeed plastic then they must be after 1900s and modern beads....that would not make them trade beads....usually they are glass like that chevron...take a look at that and compare...authentic chevrons r getting very hard to find...if you have a site that ur finding them on....those are what you want to be looking for!