kids in the garden

I've enjoyed very small successes this summer with having my kids in my garden...the 4 year old really wants to be a helper, asks if he can help me dig my very organized, thought out raised beds with a shovel and a rake (gasp!) but he also enjoyed pulling up the radishes that were ready to harvest (but he refused to eat them because I admitted to him that I dont like radishes because they are so spicy...now he wont try a nibble either...what was I thinking?!?!)...I do most of my gardening by myself during nap time...its so wonderful and therapeutic for me...but sometimes it would be nice to work on it...at least water it while the boys are awake, and I discovered that having a fun sprinkler in the backyard will keep them safely entertained for a few minutes while I water and pull weeds...but I need more ideas