Vivid colloquial. Picture reaching into a barrel of grain - 一抓 (one grab) and you pull out 一大把 (a big handful). Carries a slightly dismissive flavor: whatever it is, there's so much of it that it's not impressive or rare.
memory
Mirror with the opposite phrase 凤毛麟角 (fengmao linjiao, 'phoenix feathers and qilin horns') for things that are extremely rare.