Now, while the poster doesn't mention anything about hybrid seeds or heirloom seeds, he gets a bit of wiggle room here if he meant to specify hybrid crops. One needs to be very careful about reading and believing everything they see here.
Heirloom, or open-pollinated, crops are true to type and reproduce true to type, thus allowing one to save seed from year to year. If one saves seed from a hybrid crop, the next generation will produce something entirely different than it's parent.
Suzanne Ashworth's "Seed to Seed" is the seedsaver's bible, regarding seed saving techniques, crosspollination, cultivar habits and requirements, etc.
Google seed saving techniques for in depth and overviews. Google heirloom and open-pollinates and read about the historical importance of maintaining old varieties and read about the incredible flavor advantages of heirlooms.
Think about joining Seedsavers.org and helping preserve the old time lines of crops and help maintain the quickly diminishing biodiversity in the plant world. Consider satrting your own personal seedbank to preserve local and personal favorites.
Regarding flowers, Victoria can attest, I'm sure, to the fragrance differences between old varieties and modern hybrids.....rather the lack of fragrance that many of the hybrids possess.