It's a pair of mushrooms with legs... in holographic sticker form!
These images are two of the mushroom-legged creatures in my Anniversary Fairy Ring collage, prints of which you can buy here too! They are vinyl, removable, and waterproof... and very magical in the sun! The red capped guy is 2.8" x 2", the green capped gal is 3" x 2.7", and they are sold together as a set.
This sticker set ships in a rigid letter-size envelope. Free USPS first class shipping and tracking is available on orders totaling $50 or more.