Here is a craft for too small boots or ones no longer wanted. Place a rolled up magazine inside to keep it upright. Stuff some tissue paper, foam, or moss in the boot, artificial flowers or greenery inside, and you have a great floral arrangement.
For Christmas, you could put any type of Christmas flower, ornaments, garland, sprigs, pine cones; the list is endless. You could use live plants with any container that fits your boot. You can decorate the outside of the boot any way you like. Makes a great gift or just keep for yourself. You could also do a Thanksgiving project with boots too. Your imagination is all you need.
"Big" boots work well too for decorations (watch the 2nd hand stores). Add wildflowers to poinsettias & pine. However I finally got really smart and added a couple of rocks to the toe/foot part to keep them from being top heavy and tipping so easily. I've used one of the boots with flowers, on a bandanna square, with a new horseshoe. The "nutcup/favors" were burlap sacks sewn to just fit a bag of M&M's or package of "Sweet-N-Salty" (nuts & m&ms), and tied at the top with twine. (could even stencil feed on the bags first too!) - we've had a lot of fun with this theme. Also when using used/worn boots for dining table decors, after you've washed the outsides and bottoms, spray with low gloss lacquer--people won't question the "cleanliness" issue as much.