I think Rana is right about them being Gemlik zeytin.
Try Costco.
I love olives. But they have to be 'pure'. Not fanny-ed about with. No herbs or lemon or garlic and such.
My current favourite here in the UK are nocellara. A very bright green, 'fresh' tasting and generally unpitted olive from south west Sicily. They're only treated for 10 days and so retain a distinct crispness. Large tubs available from the deli fridge section in Costco.
My kids remind me of my shameful 'overheard in Waitrose' moment when I stood in the tapas aisle (in Waitrose funnily enough) and wailed,
'Where are all the unadulterated olives for goodness sake!'.
I know. How could I? A plain speaking Yorkshire lass like me.