Hi, its an Oxalis possibly O. pes-caprae. Hope this helps :)

Whilst it is containedin the pot it is very pretty. Try not to let it escape or it will rampage everywhere.

Commonly known as Bermuda Buttercup - rampaging on unused ground all through the south of Spain!

Thanks so much for the replies. Although it is a pretty little thing, should I try to get rid of it to stop it spreading, and keep the palm healthy and strong ?

I agree they are very pretty -you could always just keep a separate pot of them?

Keep them in a pot and dead head regularly.