Oxalis is not an important genus in local gardens, but it does provide several handsome foliage plants which, during their brief flowering period, can be very eye catching. Most of the really interesting and beautiful ones probably are not hardy here - although they are easily managed as pot plants. There are many avid Oxalis collectors; do some Googling to see what's out there.
The plant shown above is one of those borderline hardy sorts. It persists in a cold frame, but I have my doubts about its performance when planted into the garden. This species used to be known as Oxalis inops, the name under which I grew it decades ago.