Cori, not exactly sure how old your LOs is...guessing 3ish!
Other suggestions include:
water play - ds loves to stand on a chair at the sink and wash up. he has a toy teaset and likes to pour tea. Give him a teabag and he's in heaven! or let him wash his toy animals.
bubbles - those wee electric ones that you dip in a pot they can do themselves from about 2
baking/painting/playdough/park/pool/library/sandpit/paddling pool
cut an empty tissue box in half across the short side and you can make "houses" for animals or "garages" for trains.
draw a sheep, get them to stick cotton wool on for its coat, stick cut up green tissue paper along the bottom for grass
paper plate - stick orange tissue paper round the edge for a mane and draw a lion face on (you could make it into a mask)
fold paper plate in half, stick craft feathers and a beak on and make a bird
use wooden spoons or old socks to make puppets
paint the patio with water, or draw on it with chalk, or wash the bikes and trikes and scooters with warm water and sponges
paint with cars - put toy cars in paint and make patterns with their tyres
get wallpaper and put LOs in wellies, step in the paint and do footprints on the wallpaper
make gloop - cornflour and water
let them play with shaving foam or shredding paper
make a den with chairs and a rug/table cloth over top - have a picnic in it or read stories or whatever
have baths in the middle of the day (we love bath crayons though some hate them!)