Edging? Corner savers? (Amherst)

Does anyone know what these are? I have several 6' long plastic pieces of what looks like some kind of edging for tile or window trim or something else (?) The white piece looks more like a half inch track for something; the black one is 1" one side and 1/2" on the other; I was just going to throw them out but thought I'd post first to see if anyone knows what they could possibly be used for