ABCs - First Birthday. For my daughter Amelia's first birthday, I did the ABC's/Wood Block theme. 

I did the invitations on the computer. I found a clipart of three wood blocks stacked vertically. I used them as the initial letters for the wording, "Amelia's Birthday Celebration" and re-colored them in primary colors of blue, red and green and continued this color scheme with decorations and paper products.  I downloaded the "Block Letter" font, to add to the look.

Guests were greeted in the foyer filled with red, blue, and green balloons tied to the stair railing and a large jack-in-the-box popping out of a wood block with ABC on the sides holding more balloons. I just happened to have that "prop".  I had a smaller version of the same prop and used for the center piece, also holding ballons. I covered the gift table/favor bag table and other tables with tablecloths made from inexpensive ABC fabric in the same party colors and a co-coordinating fabric with child's handprints all over it.  I made the favor bags with the same fabric and put tons of wood blocks and magnetic letters inside for each child.  Each bag had a tag on it with the child's name.

For the mantle, I put four pictures of my daughter starting with her birth, 6-month, 9-month and her 1-year. I spread various wood blocks (stacked randomly) and curling ribbing (same party colors) across the mantle and put her invitation in the middle. 

For her cake, I did three square-shaped cakes for "wood blocks" with an A, B and C in the same colors as the invite and made a smaller block for her to eat/smash.  I floated letters (meant for the tub) in the punch bowl, and even froze water with letters inside it for the ice. I made cut-out butter cookies in the shape of letters, and jello jigglers in the shape of letters using basic letter cookie cutters to compliment a simple lunch buffet of deli trays and barbeque sandwiches.  I also did the thank you notes to match the invites.