Leave plastic animals in a bin outside (near the garden, next to the sandbox, next to a patch of trees, etc) -- when children go outside to play, they can use them and let their imaginations run wild! My recommendation: the children should only play with these toys outside -- that way, they'll look forward to playing outside -- make sure they run around too ;)
let the children play: Be Reggio-Inspired: Outdoor Environments
EYFS outdoor provision - music area - stainless steel mixing bowls make a bell like noise - old xylophone dismantled and strung into a chain using cable ties and stretched taught using 2 hooks - old wind chimes suspended on string and hung in a box - wooden xylophone was once a bunkbed frame - cooling rack cable tied to the fence - silicone rubber spoons for beaters (not too noisy!) - and plastic ukulele because they all want to play mine!