My dad is an avid gardener with a special love for perennial plants. For his 80th birthday, we threw a "Perennial" party built on the idea that he has kept "coming back" year after year despite trials and adversities of 80 years of life. The tables were decorated with terra cotta flower pots filled with candies, small plastic gardening tools and brightly colored pairs of gardening gloves.  At 80, Dad wanted for nothing so we had each guest bring a perennial plant along with a note telling about what he had meant to them in their lives.  The cake was white with green decorations and the room was decorated accordingly.  It was really a wonderful party and was talked about for months afterwards!