After a bit of research, it appears that white is a normal color for N. lutea. In particular, Perry Slocum describes them as anywhere from pure white to pale yellow, and there are authoritative pictures of purported N. lutea that are white and others that are yellow.
Seed provenance is always hard to verify, but I would expect that N. lutea seeds from a white-flowering selection would most likely be white as well.
As far as growing lotus from seed, the main failure I've seen is with lack of light. They need full sunlight from the time they germinate (in spring, so they have all summer to produce a tuber) until winter. The second most common mistake I see is placing them in sterile media (sand, aquatic planting media, clay, etc.). They do much better if there's organic matter and nutrients available before they run out of food stored in the large seed. If either of these needs aren't met the seed will germinate and do great until it runs out of food in the seed, and then fade away and die. You'll know you've succeeded when the leaves start to enlarge and/or it starts to produce its own tuber outside the seed. On the other hand, if the tuber doesn't get large enough before the end of the season, it may not last the winter, depending on where you live.
Beware poking at the young tuber when it's growing--it's very fragile.
