We also planted a Mulberry tree - my reasoning that it would be wonderful to keep silk worms and they love Mulberry leaves. Unfortunately, Mulberry trees are not indigenous to South Africa, so I needed to find one and work my limited propagating skills.
After successfully locating and selecting three ideal branches to propogate (with permission from the owner) only one decided to grow, and then... just as I started seeing the first mulberries, the plant disappeared! No jokes! I can only assume that because the tomatoes and capsicum were finished, the dogs decided it would be the next target.
This video may not be very appealing for children, but it will give you (and me) some necessary information if you do not have 'greenfingers' but are attempting gardening with your children.
Sesame Street also brought out a more child-friendly episode which children would enjoy and motivate them to want to plant vegetables.
Hopefully this will give you some confidence in heading into the garden with your children and starting your won little vegetable patch.