The Honeybee is but one of many insects that help pollinate plants and fruit trees. Wild bees, some wasps, flies and butterflies also contribute to pollination. You can increase your gardens harvest by planting flowers that give them nectar  and pollen sources. But to 'bee' ( pretty lame but I could not resist ) a little more specific I did a little research to discover what bees prefer.

Bees need flowers that offer nectar and are easy to access. They also like single flowering and tubular flowering plants. Bees like fragrant flowers and are attracted to the colors of lavender, blue, purple, yellow and white. Providing flowers throughout the growing season is another big boost for attracting bees. Flowering trees and fruit trees provide early nectar sources. Having a large amount of the same flower blooming at the same time is also favored by bees because they only visit one type of flower on each nectar gathering trip.  Here is a short list of some bee attracting plants: Ajuga, clovers, flowering cherry trees, joepye weed and Russian sage.