Flowers cross-pollinated between two different varieties produce seeds with the traits of both parents. A white marigold with single blooms crossed with a light yellow marigold with double blooms might produce seeds that grow into cream-colored, double-bloomed marigolds.
Seeds collected from marigolds that grew from hybrid seeds are second generation, or F2 seeds. The DNA in these F2 seeds have all the traits from the original plants the hybrid seeds were created from. Each seed has a different combination of the traits.
Each seed taken from a white hybrid marigold has a different combination of traits belong to the plants used to create the original white hybrid seeds. These seeds will grow, but the results will be unpredictable. Some might be white, others may be different colors, have different size blooms, or feature different types of blooms.