I know this is just a meme, but in case anyone thinks it's real, it isn't. I can't find any mention in Sappho's poems about broccoli nor any articles on queer history of lesbians giving out broccoli at any point.
Remember: if it seems ridiculous or too good to be true, it probably is and deserves some research to confirm so you aren't spreading misinformation or more malicious disinformation.
There's also this blog post on it, but it alone also isn't a reputable source. I just can't find anyone else who actually dug into this and wrote about it.