If you’d rather have plants than seeds, I will have some seedlings from various criollo varieties in the next few months-not all have pure white seeds, but I do have one with pure white seeds (it comes from a seedling criollo tree). Other varieties are Soconusco (not strictly criollo, but a famous heirloom variety from Mexico-mainly light purple seeds, some have white splotches), and a Puerto Rican heirloom with a mix of white and purple seeds. In addition, if you’re looking for a genetically important and cool variety, I will have some Pentagona (a very rare variety from Venezuela-purple-pink seeds, but pod has distinctive ridges making for a pentagonal cross-section of the fruit) seedlings too, as well as round leaf jaca and Heirloom Nacional. If you’re interested in anything, let me know, and I can reserve whatever you’d want.
Though cacao doesn’t grow true from seed, most criollo and other heirloom varieties grow very similarly if not identically to their parents-the genetics might be slightly different, but the characteristics will mostly stay the same. So a white-seeded cacao seedling will most likely produce white seeded fruit. The reason for most air layering and/or grafting is for highly-hybridized varieties, as those are bred carefully and slight genetic differences might change the characteristics.
Criollo is supposed to make higher-quality chocolate because the white seeds contain less bitter compounds (Aztecs I think bred cacao to have white seeds, to more closely resemble the taste of Mocambo while still having more caffeine and theobromine). That doesn’t always mean criollo chocolate will taste better to everyone, especially if you add anything which is almost always added to chocolate, like sugar and milk. Criollo generally gives a milder, more complex flavor. I describe Criollo as any cacao with white seeds. In the modern context, Trinitario generally means modern hybrids made to taste better while still giving better flavor, and they are usually purple-seeded, stronger tasting cacao with some complexity. Forastero generally means modern hybrids bred for productivity and ignoring taste, but, for example, Nacional types are technically “forastero” types. I personally use Trinitario and Forastero to describe modern hybrids, and specific names to describe old heirloom types, for example Pentagona, Porcelana (though that’s a criollo, it deserves its own name), Nacional, Soconusco (named after its locality), etc.
Hope my rambling is helpful!
Tomek