A couple more "quick" inquiries

local function RandomResourceSeed()
	local iMaxX, iMaxY = Map.GetGridSize()
	local bValidPlotFound
	while not bValidPlotFound do
		local iX = math.random(iMaxX)
		local iY = math.random(iMaxY)
		local pPlot = Map.GetPlot(iX, iY)
		if pPlot then
			-- Plot exists; stuff additional terrain/feature checks here as necessary
			local tempPlotTable = {pPlot}
			-- Fill in the table with adjacent tiles
			for i = 0, DirectionTypes.NUM_DIRECTION_TYPES - 1 do
				local pAdjacentPlot = Map.PlotDirection(iX, iY, i)
				if pAdjacentPlot then
					--Plot Exists
					-- Stuff more terrain/feature checks here if you need all surrounding plots to abide by the same rules as well
					if pAdjacentPlot:GetTerrainType() == TerrainTypes.TERRAIN_TUNDRA then
						table.insert(tempPlotTable, pAdjacentPlot)
					end
				end
			end
			if #tempPlotTable > 3 then
				-- This would only run if the table has more than 3 entries in it (Worst case, a corner tile would only be able to find 2 other adjacent tiles.)
				-- You can increase the number to however many tiles you need at minimum.
				local iResourceCount = 3 -- However many copies you need to place
				-- This is where you can place JFD's table randomization code
				for i = 1, iResourceCount do
					local bResourcePlaced
					while not bResourcePlaced and #tempPlotTable > 0 do
						local iRandomIndex = math.random(#tempPlotTable)
						local pTargetPlot = tempPlotTable[iRandomIndex]
						-- Additional checks here if you want, if you didn't already filter them in the previous loop
						pTargetPlot:SetResourceType(GameInfoTypes.RESOURCE_SECRET, 1)
						bResourcePlaced = true
						table.remove(tempPlotTable, iRandomIndex)
					end
				end
				local bValidPlotFound = true
			end
		end
	end
end