[KarenO]

be very careful of "wildflower" seed mixes. be sure to read what is in it, they often contain very problematic plant seed.
1. one person's wildflower is another person's invasive weed
2. Planting ornamental flowers, annual and perennial and blooming shrubs or fruit trees are overall more useful and less likely to cause a problem for you over time.
3. Planting a row of flowers in your vegetable garden is a good idea but use nice annuals such as bachelor buttons, cosmos, , zinnias, etc and you can use them for cutflowers as well as to invite pollinators to your garden.
4. I agree that dill and fennel are both very attractive to the best pollinators which are the solitary bees and small wasps.
5. If I wanted to sow a crop to specifically feed bees nectar, and I had the space, I would use red clover or alsike clover. both fix nitrogen and are not very invasive both are also attractive and make high quality nectar. What honeybees want more than anything is pollen as a protein source for their larvae. Trees are actually most likely the very best sources of pollen for bees. If you want flowers specifically for pollen, consider composite flowers, members of the Asteraceae family such as daisies, asters, sunflowers, cone flowers as good pollen producers as well as golden rod. (there are cultivated varieties that are not so weedy as well as thistle, again not the weedy but the ornamentals such as globe thistle)
The honey is produced mainly to feed the workers in the hive.
As far as pollinating vegetables etc, the small native solitary bees and wasps and other small insects such a flies are actually more important than non native honeybees.
KarenO