The complex relationship between native bees and their wildflower hosts is fascinating. In the near future I plan to create a welcoming space to study their interactions in my own backyard but in the meantime I'm content to observe them in the wild.
Fun fact: the largest bee I've observed is a 1" long male Xylocopa varipuncta and the smallest is a 0.1" long Ceratina spp (possibly C. cockerelli) and both are in the subfamily Xylocopinae.
Books: The Bees in Your Backyard, California Bees and Blooms