create sample from feature collection

Get the centroid of each feature

// import lc feature collection
var lc = ee.FeatureCollection("users/servirmekong/cambodia/Landuse2002")

// import feature collection
var provinces = ee.FeatureCollection("users/servirmekong/countries/KHM_adm1");
// import surface reflectance composite
var composites = ee.ImageCollection("projects/servir-mekong/yearlyComposites");

// filter for province
var province = "Batdâmbâng";

// select province from feature collection
var myProvince = provinces.filter(ee.Filter.eq("NAME_1","Batdâmbâng"));

// filter for aoi
var lc = lc.filterBounds(myProvince);

// print all classes
print(lc.aggregate_histogram("NAME"));

// function to get the centroid
function getCentroid(feat){
return feat.centroid();
}

// filter for paddy rice and get the centroid
var rice = lc.filter(ee.Filter.eq("NAME","Paddy field")).map(getCentroid);

// add the points to the map
Map.addLayer(rice,{},"rice");