Whimsical presents for children are always appreciated. Many Irish grade-schoolers collect erasers in different shapes: animal shapes, cartoon characters, and that sort of thing. State pins and US "souveniers" from your home are also a lot of fun.
One of our family heirlooms is a beret that has been added to by several generations with small souvenier pins of their travels. Some of the pins include sporting events in other European countries, similar to the popular Guardian angel pins found in the greeting card shops.
A large supply of small, thoughtful gifts is a wonderful way to make your stay remembered fondly by the many generous people you will surely encounter on any trip to Ireland.
Bon voyage,
Mary Ellen