These are indeed four Chinese Blue-and-White Porcelain pieces, specifically from the Qing dynasty (19th/20th century). Here's a more detailed analysis:

Unknown artist 19th/20th century

Medium

rice bowl and cover painted with peonies, some edges bound in brass, teapot with four lugs for attaching bamboo handles, abstract painted scene on one side and calligraphy on the other, two small ginger jars painted overall with abstract floral patterns

Category

Ceramics