Do you have any plans to cultivate this area, CBG? Apparently it was at some time in the past...someone planted your yellow tulips, and what I think is a pink one at the top R. of your photo. Am sure that the bevy of plant mavens here at the Forum could supply help in how to cultivate, what plants should do well in your climate, etc.
I just let the Euphorbia, believe it may be the same variety as you have there, go where it wants to , it doesn't seem overly aggressive here. Best handled with gloves though, to avoid skin or eye contact from the sap which can be quite irritable.