Rubber
Single-use rubber items like balloons pollute the environment and can be harmful to wildlife. Choose easily compostable/biodegradable ones.
Rubber items made from rubber sap (natural latex) are biodegradable, but may take 15+ years to decompose, so it's better to reuse them. Synthetic rubber made from oil takes several times this long.
See rubber band
Choose easily compostable/biodegradable balloons.
Choose to purchase biodegradable food prep gloves where possible.
Compostable rubber gloves for dishwashing, gardening, household cleaning are available in New Zealand.
Inner tubes of bicycle tyres can be reused in many creative ways, for example earrings, wallets, phone pouches, mats. Check online.
Rubber gloves can be filled with cement to make garden-container "hands" to grow plants.
The sleeves of rubber gloves can be cut into rings to make large rubber bands.
The finger tips of rubber gloves can be cut off to make finger puppets. Use a permanent marker to draw different faces.
If you are looking for matting made out of recycled rubber, try locally-owned and operated Burgess Matting.