Hey, and the envelope with my latest order of stamps (from a seller in Belgium) has stamps with tulips on.
Issued 2003 in booklet panes Perf. Die Cut 9¾ on 2 or sides
1991 A858 0.59€ Multi-colored Yellow Tulips
Windmills
Issued 2002, Jul. 15
Perf. 11½ Photolithogr.
1925 A824 0.42€ Multi-colored Onze-Lieve-Vrouw-Lombeek windmill, Azores
[Source: Scott 2018 Standard Postage Stamp Catalogue, Vol. 1B]
Issued 2002, Jun. 10
Perf. 11 ½ Photolithogr.
1917 A820 0.42€ Multi-colored Leffe Abbey, 850th Anniversary
Belgian Castles
Issued 2002, Jun. 10
Perf. 11 ½ Photolithogr. Mini-sheet of 10
1918a A821 0.42€ Multi-colored Ecaussinnes-Lalaing
1918c A821 0.42€ Multi-colored Corroy-le-Chateau
1918d A821 0.42€ Multi-colored Alden Biesen
1918e A821 0.42€ Multi-colored Modave
1918f A821 0.42€ Multi-colored Horst
1918j A821 0.42€ Multi-colored Wissekerke
[Source: Scott 2018 Standard Postage Stamp Catalogue, Vol. 1B]
Issued 2005 (types of 1985 with Euro denominations)
Perf. 11 ½ Photolithogr.
2072 A524 0.05€ Multi-colored Bruant zizi (Belgium Cirl bunting bird)
Issued 2023, Jan.23
Perf. Die Cut 11½ Litho. Self-adhesive
Registered Mail Multi-colored Red-Knot Sandpiper
[Source: Scott 2018 Standard Postage Stamp Catalogue, Vol. 1B]