My guess is one of the Chinese mustard greens. See this link for additional info

I would guess the India mustard Florida broadleaf. Too little info to be definite tho.

It is a giant mustard for sure, unless you have truly tiny hands.

how about a picture of the plant?

Is there a visible enlarged root? I wonder if it could possibly be horseradish.

not horseradish. leaves are too pale, too wide, too opaque. Edge of HR is smooth too.

Ok thanks :)

I say broad-leaf mustard as well. Quite edible, regardless of what strain of mustard it is..