I had this plant in my garden where I'd tossed out some "friendly bug mix" seeds. I thought it was clover, but it didn't look quite right. I'd been wondering what it was for over a year when my mum finally pointed out that it looked like lucerne (or alfalfa). Its so silly that I didn't recognise it, but I'm used to seeing lucerne dried as hay and I'd never really seen the living plant. Now that really got me thinking because I remembered reading somewhere that lucerne tea is really good because the plant has such deep roots and accumulates lots of minerals, but I didn't want to use any of the hay we buy because you don't really know "where its been" so to speak. I forget now where I read that, and when you goggle lucerne or alfalfa tea, most of the links are about making tea for your garden rather than for yourself! (here's one semi-helpful link) Anyway, I didn't think it would hurt to cut some of the lucerne leaves and dry them to add to my herbal tea mix. I've let the plant flower (lovely purplely-blue flowers) and hoping it will produce some seeds, as I'm not getting many leaves off the one plant. I'm so glad that I finally identified it and didn't pull it out as a weed.
I dried some in my dehydrator and it doesn't really change the taste of the tea, but I'm hoping it adds some good things to my normal mix of herbs.