Have lots of fun teaching your little tikes about the alphabet and recognising sounds as a great introduction to the skill of reading.
Collect and have on hand, lots of small toys and objects that your little tike will recognise and know the name of. The game is one of your little tike recognising and saying the first sound in the name of the object. You are going to try to have one object for each letter in the alphabet but don't go to the bother of having every letter. By having one object per letter you should widen your tike's awareness and skill in recognising different letter sounds.
The guess where you're going to hide the objects - in the lovely mud pie of course! You could also use pictures or photos (realising they will be covered in mud). For example a toy truck = t for truck, a duck = d for duck and so on. Get your little tike to have great fun and excitement in reaching into the lovely, icky, gooey mud, finding the objects and putting them in a bucket for sorting.
Use lower case magnetic or wooden alphabet letters. Place them across the lawn or wherever is suitable in alphabetic order to help your little tike with alphabetic order. Tell Little Tike it is his/her job to reach into the lovely mud to find a surprise and sort them by their beginning sounds. As Tike pulls an object from the bucket, have him/her say the first sound (eg wheel = w) and then they place the object under the appropriate letter. They may name the object differently to how you have, for example tractor wheel = t, but that's okay. Go with whatever they name the object for maximum enjoyment. You say, "What is it?" Tike responds, "A coin!" You say, "What does coin start with?" Tike replies, "Coin, c, c, c."
Once you've finished saying the beginning sound for each object pack them up and put them back into the bucket. Then you could scramble the letters up and have your little tike put them into alphabetic order.