There are lots of lists that are available and a group of experts should be able to just choose one. As it turns out very little actual research has been done on which plants are actually attractive to which pollinators. Most lists end up tracing back to anecdotes from someone’s grandmother who saw a bee on a particular plant way back when. As an industry we have just funded research to try to understand this much better. Each different pollinator has different preferences in terms of flower color, time of day, temperature and other issues.
Recently, a Plant Something member attended an international symposium on native bees. There was a huge amount of discussion on this exact question. The consensus at this point in time, until definitive answers are reached, is that any flower is a great addition to the “pollinator buffet table.” They were far less concerned with exactly which flower was planted, and much more concerned that the public actually planted more flowers of any kind.
They can point you in the right direction and give you tips for success. You can find them here.
Shrubs and trees