Having been a daycare teacher for over 20 years, let me give you the teacher's point of view... realizing that this is only one teacher's point of view, but that many will feel the same way. We don't expect gifts at Christmas or any other time of year. But, the little things you might do to show appreciation are nice. If you want to give something, let it be something that allows your child to participate, because a teacher's heart is warmed more by knowing you are teaching your child to appreciate her (or him) than by you showing you can find the most unique or extravagant gift. Do baked goods and/or a craft together with your son. Don't expect them to come out perfect, because the teacher will love seeing the child's work in them. Some suggestions... a special tree ornament (include a small picture of your son on it if you'd like to do that), cutout and decorated cookies... either edible or make up a gingerbread playdough (recipe below) and dry them (can be made into tree ornaments as well), if you have a special "secret" family recipe of any type, perhaps make that up to give. Personally I'd love a good homemade soup being brought for my lunch one day. Since you mention there are at least four people who work with your child, if they get together for lunch, that might be a perfect way to show appreciation. You can even join forces with other parents and each bring something. The things I recommend you AVOID are storebought sweets because teachers tend to get overloaded with that type of thing, perfumes, costume jewelry.
Recipe for gingerbread playdough.
1 cup flour
1/2 cup salt
1 teaspoon cream of tartar
1 cup cinnamon (buy the cheapest you can find)
add smaller amounts of ginger, cloves, allspice to the mix if desired.
Mix all of that together, then begin adding water to make a stiff dough. Knead the dough well, and store in a zip lock bag or tightly covered container until ready to use.
To make items, knead the dough then make free hand forms or roll out to about 1/3 inch thickness and cut with cookie cutters. If making a tree ornament, use a pencil or other tool to form a hole at the top to put a string loop through for hanging. Put the finished product in a warm place to dry (takes about a week, depending on thickness of the item) turn the items each day to allow for even and complete drying. You can also put the items into an oven set on the lowest heat (mine is 170 degrees) for several hours to speed up the drying.
One of my favorite things to do with this for the parents is to take a rather large lump of the dough, form it into a heart shape about 1/2 to 3/4 inch thick, then help the child make a handprint in the heart. I take a pencil and put the child's name and the date on the edge of the heart.
These may take up to two weeks to dry because of the extra thickness. If you have a cooling rack, it helps to put them on that, but use a piece of wax paper... or even just a sheet of plain paper under them so they don't stick to the rack.