I rent, so I got a limited space to work with. That said, I counted 12 bees buzzing my 3 anise hyssop plants (Two are 2 years old in the ground, 1 in a container from seed this year) and my (Monarda Citriodora) lemon bee balm! This is the most I have seen in my yard so far!
Walking conservation areas around here I've noticed they show extreme preference toward common milkweed and butterfly weed, and somewhat to nearby mountain mint. I have seen a few buzzing my salvia as well.
What other native species have you seen bees go crazy for?
Native Allium has had a lot of success for me; I've seen a variety of bumble bee, wasps, carpenter bees, and cuckoo bees on them this year. My Monardas and coneflowers are always very popular. I've seen some decent activity on my Gaillardias too. Unfortunately I haven't seen much activity on my non-cultivar sunflowers but the little activity I have seen has included some really interesting Ichneumonoid wasps.
Zone 5b northern plains
If you're in the US, I recommend aster. They bloom in fall and bees love them. I have bush growing in my yard and last fall it was completely covered with bees every day until winter. The bushes aren't large but they don't really looking like much until fall.