At what age do they stop putting everything in their mouths?

[Disenchanted3]

DD is 9 months and I spend my whole day saying 'DD...NO!' and retrieving a penny / piece of fluff / leaf from her mouth!

usually around 2 some earlier some much much much later, i work in a nursery and am constantly telling my room 2-3's and the 3-5's not to put things in their mouths i say about 2.5 - 2.8 they kinda dwindle then stop.

About 18 months with my ds but my friend's nearly 3 yr old still does it all the time. Think it depends on the child!