Yes I give my kids a tub of oats to play with. It is the best sensory bin EVER for us.
Stella can eat it - no harm done.
Anna and Kate play and play, they pretend, stir, dig, pour and just run their little fingers through the oatiness. Sure it goes everywhere, but nothing a broom can't fix.
I bought a 1kg bottle of oats, we just clean them up back into the bottle. Sure you lose a few oats with every play, we have had ours out about 6 times and still have over 3/4 of the bottle.
Go on give your kids some oats , take them outside if the mess stresses you out.