Here are a couple activities that I've created for St. Patrick's Day:
Pots of Gold
I made construction paper pots of gold with numbers on them. Then I made little circles out of gold construction paper. The children can count out the number of gold pieces and match them to the numbered pots. I'll use pieces of velcro, so the children can attach the pieces of gold using velcro.

Shamrocks
I made shamrocks out of green construction paper. One set has black circles on them, and the other set has numbers on them. The children can practice counting the number of circles and then match to the correct numbered shamrock. Again, I'm using velcro so the children can attach the shamrocks to a piece of white cardstock.

Other ideas:
You can also create different sized shamrocks or pots of gold and ask the children to put them in order smallest to largest or vice versa.
Create shamrocks that have different shapes on them or are different colors. The children can play a matching game based on the shape or the color. You could also hide shamrocks around the room and ask the children to look for them, then count how many they find.
Use only the numbered shamrocks and ask the children to put them in order 1, 2, 3 etc.
Also, if you have a sensory table, you could fill it up with scrunched up paper. Hide shamrocks underneathe the paper. The children will have a great time looking for the shamrocks. I did this activity using a long cardboard box and pieces that were falling off of an old pom-pom. It was fun looking for the shamrocks, but it may have been even funner simply throwing the pom-pom pieces all over the place.
- Michelle