I have a sudden abundance of free time so that's how I learned maple blossoms are edible, and also that they're abundant in the woods near my house, and also how I was able to gather up a bunch of them in the middle of a Tuesday.
These are the blossoms of big leaf maple trees and basically if you look up in a Pacific Northwest forest in spring and you see you yellow you're probably looking at them. And don't worry about having to climb a tree to get them because Spring is windy and these things just rain down on the ground to be easily gathered up.
What can you do with them? Great question and I have the same one. I've read that some people fry them up as fritters, but I had dreams of turning them into something called "jonjoli" and if you haven't spent time in the former Soviet Union then don't feel bad if you don't know what that is. Over a decade ago I lived in the Republic of Georgia where I served as a Peace Corps Volunteer for over two years. While there I met my future wife (fellow volunteer), adopted our current dog, and developed an enthusiasm for pickled bladdernut blossoms during dreary winters devoid of green veggies. Jonjoli was that pickled green vegetable that I would eat between wine toasts and more toasts, and animal horns full of wine, and more wine and then maybe some vodka. While my liver is probably no better for the experience I never did get scurvy.
If this were a popular food blog this story would lead to me reconnecting with this prized food using locally-sourced ingredients, but unfortunately maple blossoms don't work like that. They are bitter (unless boiled in salt water), they fall apart when pickled, and they seem hard to utilize in any sort of redeemable way. That said, even though I struck out this year I'll be trying again next year. If you know what to do with these things please let me know in the comments!