Occasionally i dither over i should get a sunflower lanyard, however i am a little worried about the help that it would invite would be of the condescending sort, given that the common perception of neurodiversity is not a kind one in most areas.
Furthermore, i do wonder if it would be of any practical help, or if it will just invite unwanted attention.
So does anyone have any experience with it? I am hesitant to get one and i am interested to hear if it's useful to anyone here.
aw i very much understand your worry about a lanyard like it garnering unwanted or condescending attention 
i think that fear shapes my use of it, which is very limited. the few times i've worn it have been for myself, and explicitly in situations where people in a position of more authority would be aware of what it means. from what i recall, i've mainly worn it during security control at airports, job interviews, and a few times during meetings with public services. i'd like to think it creates the expectation that i may interact differently from the norm in a soft, non-intrusive way that doesn't require me to say anything. in that way, i have to worry less about how i come off when i'm being questioned at the airport, especially worrying if my lack of eye contact and body movements make me look suspicious, and more just on answering the questions.
i also fashioned a sunflower lanyard into a little bow to pop into my hair for one or two social occasions where it turns out i didn't know anyone, so i could also signal i might behave a little differently. i don't know what sorts of circumstances u were thinking of wearing it for, but i think personally it's helped me relax a little, even if i don't know how the people with authority register it it is also a good deal normalised here too, which also helps.