You would grow any type of bee-attracting flower that blooms at the same time as your vegetable is blooming. I think it would be hard to get seed-started flowers to bloom in N. Michigan before squash blooms opened. You may want to try putting flower plant starts in the ground. Seeded perennials might work from the second year on. Squash can be hand-pollinated. Winter squash such as butternut can be tricky in short-season climates because the male flowers seem to open weeks before the female flowers start, and that doesn't leave much time for full-sized squash to form. Even in Portland (zone 8), we only get about a 3-week window where forming squash go on to become full-sized.

That is too bad that the bees are a risk to your daughter. I hope she stays safe. I love the little critters buzzing around my flowers and there are zillions of them out there now. The more the merrier! I regularly work in the middle of them and have yet to be stung. But you have to remain calm which is hard to do when people are afraid. I can only think to add Peonies to this list. I have a hosta that is blooming right now with plain green leaves and pretty purple and white streaked flowers. The bees are all over it. Also normally I would agree about Daylilies, but a very odd thing is happening with some Daylily flowers this year. I will find 5 to sometimes 8 or 10 little bees inside certain flowers throughout the day. They seem to be hanging out in there in a group. Never saw them do this before. Here's a pic:

From what I've read, the most important thing you can do for bees, is to have plants they like throughout the growing season. Since we're in different zones, not everything may apply, but in our area, hyacinths seem to be popular in the spring, as are apple and plum trees. Lavender and spearmint are always a big draw and mine seem to love any rose they can fit into :) Alyssum, stock and cosmos are all getting some notice right now, and butterfly bushes and coneflowers were popular in the later summer. Sunflowers, marigolds and zinnias seem to keep them happy in the vegetable garden. As long as there is something for them all spring/summer, they should stay around and come back next year.

Looks like your'e doing the right thing! Varieties is the key to bring bees to your garden..there can be some bad tasting honey from certain nectar source, not sure about onion's, I never had any problem but some beekeepers south claimed the fall honey from aster, goldenrod smells like sour socks. Even when you think your apples and cherry are in prime time for bee activity it doesn't mean you'll have bees, they concentrate allway's first on the best available nectar/pollen source. Pear and plums are especially bad because the nectar is very low in sugar content.