This is called a “shamrock plant.” I found some growing in a pot outside and got excited because I thought I’d found 4 leaf clovers. It is really Oxalis regnellii, or sorrel.When I was looking up the plant, I kept seeing the oxalis regnelli listed as a purple shamrock, but I’m going to defer to the USDA plant website, which pictures the green variety; triangularis has the red purple leaves. Its leaves are edible in small quantities (but the website I’m linking to notes ALL of it is actually toxic; it’s just low in toxicity. Hmmm).