HEX CODES
#939A8B
#636D57
#7E8279
#434A3C
#6B7E75
#244133
#66716B
#1C2D25
#D8D9D7
#C7C9C6
#A9AAA8
#838482
#E1D4BA
#D4C19D
#AEA696
#8B7F68
#DCC694
#CDAE65
#AA9D7E
#867344

Original image from Bruno Luz

Five colors with tint, shade, and tone of each for added inspiration. Includes HTML/HEX codes.