It is possible to ID trees before they bloom, but it's so much easier knowing what the flower, seeds, and fruit look like.
Borage, which is the most prolific annual I've ever seen. It actually lives less than a year and replaces itself in generations. Blooms in 6 weeks. And comes back every spring. Has stiff thorny hairs on old leaves.
Butterfly Weed, (Asclepias, not butterfly Bush) Bees do like Butterfly Bush but the flowers are a bit to deep for them. So you'd need a hedge of Butterfly Bush to get their attention. Butterfly Weed, Asclepias, is native to the US, and more bees go after it per flowers. It's also the host plant to the Monarch Butterfly. Bees tend to get bits of the flowers stuck on their legs though. Asclepias tuberosa
has a very intense orange flower.
Liatris (Also called Blazing Star, or Gay Feather) is a good wildflower you can usually buy in garden stores. Bulbs are best becuase the plant is a biannual. I've never really been able to keep these plants alive more than two years though, But I've been planting them like crazy. Hopefully I'll get a nice population going. The bees are nuts for them. Birds such as the Gold Finch go for the seeds too. A little expensive if you're just planting seeds somewhere though.
Sunflowers, can't go wrong planting assorted varieties of these, in assorted heights and colors.
I don't know if they like Black Eye'd Susan but I know bees enjoy the related Sneezing weed. They like Cone flowers too but they're not that much of a draw.
All of these make good bird seed too for Gold Finches.
Joe Pye Weed was an amazing perennial. Dying back to the ground every year, it actually grows 4 to 7 feet tall (or more) and has sheets of sweet smelling flowers. I had a single plant that was covered in bees last year. You can buy a dwarf variety in garden stores but much larger ones are available. Bone Set is a related plant that's smaller and has white flowers. I don't know if bees like that one but it's worth a try. Joe Pye Weed
Clethra alnifolia is a wonderful shrub. Has the BEST fragrance I've ever smelled from a plant. But it tends to get way to much attention from our native bees. This thing really brings out the rarely seen Scoliid wasps
and dozens of others you wouldn't have known existed.
Goldenrod is probably the best fall crop you can plant. Very common road side weed, that's humorously being sold in garden stores now. It sends up suckers every year and reseeds a wide area.
Asters are also great too.
You can always go the orchard rough and plant any number of spring flowering plants. Just make sure they have enough cold hours so they don't bloom to early in the year. An early frost can kill the blooms.