Anniversary milestone's theme are quite special. 
Each year, something to consider and look forward to...

Here's the full list! 

1st Anniversary: PAPER

2nd Anniversary: COTTON

3rd Anniversary: LEATHER

4th Anniversary: FRUIT or FLOWERS

5th Anniversary: WOOD

6th Anniversary: CANDY or IRON

7th Anniversary: WOOL or COPPER

8th Anniversary: POTTERY or BRONZE

9th Anniversary: WILLOW or POTTERY

10th Anniversary: TIN or ALLUMINUM

11th Anniversary: STEEL

12th Anniversary: SILK or LINEN

13th Anniversary: LACE

14th Anniversary: GOLD JEWELRY

15th Anniversary: CRYSTAL

19th Anniversary: JADE

25th Anniversary: SILVER

30th Anniversary: PEARL

35th Anniversary: CORAL

40th Anniversary: RUBY

45th Anniversary: SAPPHIRE

50th Anniversary: GOLD

55th Anniversary: EMERALD

60th Anniversary: DIAMOND

65th Anniversary: BLUE SAPPHIRE

70th Anniversary: PLATINUM

75th Anniversary: DIAMOND, GOLD

80th Anniversary: OAK