Answer: Your choices are limited, as most flowers take 90-120 days, or longer, to reach bloom from seed under ideal conditions.
Marigold is a fast grower, but it can take 90 days to bloom.
Here's some with the least days to maturity. Of course, different varieties will have different days, so check seed packs and catalog descriptions.
phlox drummondii, 'Tapestry Mix' 50-65
Q&A Library Searching Tips