Borage, which readily re-seeds itself and Penstemon - my personal favs, Rudbeckia, Sunflowers (yeah, not perennial), and lots of the herbs.

The bees here in CA love Vetch, Borage, Nasturtium, Sunflowers, which are all self seeding annuals....

Vetch is a good nitrogen fixer and the others all have edible parts.

I second the vote for penstemon. Echinacea (coneflowers), agastache (hyssops), and salvia (sages) are also good.

One of my favorite plants is bronze fennel. It's a perennial herb with dark ferny foliage and when in flower it draws in pollinators from miles around (or at least it seems like it).

Rodney

The plant which will best attract pollinators is the crop itself. There is no value in attracting honey bees, for example, if you are trying to pollinate tomatoes. Honey bees don't pollinate tomatoes. Tomatoes will attract the right pollinators for tomatoes.

Jim