Do you know a great collaborative field recording's website where you can post, share and download field recording's sound for free ?
Thanks for your anwsers
closest answer is the sound collector's club. Its not free, but its very cheap - and its super high quality, so well worth the price of admission.
The Freesound Project
Depending on how good your dutch is (or your skills at translate.google.com) check out this.
Disclaimer: I conceptualized and set this site up in collaboration with the Dutch Instute of Sound and Vision. It's got over 2300 professionally recorded sounds from archives and users. You can contribute also, but it's intended as a Dutch sound archive.
So it may not be very meaningful to contribute sounds from your country. But invite you to have a look at it. We use soundcloud by the way.