The phrase "white button" refers to a small, round/flat object that is typically white in color and can be pressed. It can be used as a symbol for simplicity or ease of use, often seen in technology or devices. Full definition
Models were styled with a minimalist flare, including a straight leg crop denim with crisp white button down shirt, and an elegant all black wide leg pant and off shoulder top. (lovezahra.com)
They go with a spectrum of tops from colored and printed t - shirts to plain crisp white button up shirts. (outfittrends.com)
Toss finely chopped (not minced) white button mushrooms in the butter to coat. (remonline.com)