Preheat oven to 170C.
Thoroughly wash the greens and chop coarsely.
Steam or blanch the greens (including the stinging nettles) for 5 minutes or until slightly tender. Drain and set aside.
In a heavy skillet,heat a tablespoon of olive oil. Add garlic,drained greens and artichoke pieces. Saute for 3 minutes and set aside.
Place the ricotta in a large bowl. Crumble in the feta and add the olives,lemon zest,thyme,salt,pepper and nutmeg.
With a spoon,incorporate the greens and artichokes into this mixture. Set aside.
Brush a 21cm springform cake pan with olive oil.
Open the packet of filo and remove 10 sheets. (The remainder can be refrigerated for other cooking.) Divide the 10 sheets into two stacks.
With one stack,cut in half vertically to create two equal half batches of filo. With the other stack of full-size sheets,cut into 18cm-diameter circles and cover with a tea towel (to be used for the top later).
Layer the halved filo pastry sheets in the pan,coating each layer with olive oil. Keep working around the form,to make sure the pan is evenly covered and allow the long pieces to overhang. Spoon in the ricotta mixture.
Cover mixture with the round filo and be sure to brush olive oil between the layers. Fold in the overhanging bits to complete the pie.
Brush the top with olive oil and bake for 30 minutes (check often so as not to burn it).
Cool on a rack and serve warm or chilled.
*If using stinging nettles,prepare them by placing in a sink of water for a few minutes. At all times have gloves on. Wash then drain in a colander. Chop them coarsely before adding to the other greens.