Sycamore is a lovely wood to carve, and is used for all sorts of treen. Not only spoons but bowls, cups, shrink pots, rolling pins, almost anything. I have gone off it a bit for spoons because it has no character and can appear bland, and I now prefer beech. Sycamore is a readily available wood and perfect when green for spoons.
When dry or nearly dry it can be very hard, so best do all roughing out and rough carving when green. I tend to let my spoons dry before giving them there final knife finish. Always make sure you use a maximum of half the log/branch only. Preferably use a 1/4 or less, this way you are less likely to have splitting problems. Make sure you do not include the pith in any part of your carving.
Once a spoon is carved then just let it dry, there is really no need to wrap in anything, just do not dry rapidly or subject to heat. If you need to keep the spoon green either leave in a plastic bag or pop it into the freezer.
