A plastic tray (not necessarily round, garden centers are a good lace to find them)
Some moist soil,
Bottle or jam jar lids and acorn cups ( these are to make ponds)
Small stones or shells
and a selection of plant cuttings, twigs and flowers (do make sure you have permission before picking any flowers)!
Then let your imagination run wild as you create winding paths, little hills and secret pool in your ‘Wonder Garden’.