If you live near a Lego Store, kids ages 6- 14 can build and take home a free Lego model each month. On June 5th, kids can build and keep a free Lego Lawn Mower. Check with your local store to make sure that they are participating and also ask what time to you need to arrive.
From the Lego website:
The LEGO Store Monthly Mini Model Build!
One day each month you can learn how to build a cool LEGO mini model, and take it home – for free! Quantities are limited and offer is good while supplies last only. A new model will be available every month and will be specially themed to that month – ask a Store Associate for details! Models are not for sale and cannot be purchased. One free per child. Event is open to children aged 6 to 14 only. Check with your local LEGO Store for dates and times.
Here is the link to find out more about Lego store events and find your closest location.