Hi Kevin, here are some nice videos that focus on trees as they provide huge amounts of nectar and pollen for our bees. The trick is to plant a series that provide at different times of the season. Both are by Mike Connor
https://www.youtube.com/watch?v=uI-i-aj34Vc
https://www.youtube.com/watch?v=PCPj3U8uvAk
Frederick Dunn advocates the little leaf Linden tree
https://www.youtube.com/watch?v=tuwJLo751bQ
Frederick Dunn advocating various plants for bees
https://www.youtube.com/watch?v=kklvJeUFTos
I have had good success with lavender of all types, mints, sunflowers, zinnias, and winter squash. None of them cost much and once established the lavender needs little care. Mints of course are better in containers or someplace that you don't care if they overrun everything else.