Can you name this plant

Can  anyone identify this plant. It comes back every year with small pink/purple
flowers around March to April. The closest I can find in my books is Oxalis but
they say it is a rockery plant in July to August. This is in the open ground under
a tree and gets little if any attention. It even takes being trampled on by the
grandchildren. But it bounces back every time.
Any ideas ????