I'm starting to collect seeds just for trading and donating. Everything is just open-pollinated from my yard. I have multiple cultivars of the sames species like three 3 different Rudbeckia hirta cultivars (seed started). If I collect seeds from one should I indicate the cultivar on the label or will the seeds most likely not come true and so should I just label them Rudbeckia hirta.

I'm not sure which plants self or cross-pollinate. Do people just label seeds as being the same cultivar or color as the parent, but say it is open-pollinated?