Things we've bought at Dollar Tree over the last year or two:
Foil pans, paper plates, silverware, cups, napkins, tablecloths
cards, gift boxes/bags, tissue paper, bows
name brand candy---pop rocks, Werther's, etc.
name brand handsoap, mini tissues for the boys to take hiking/camping
Disney branded stockings! The one by my old house had them in 3 sizes, and with either Mickey Mouse or Princesses on them (red and pink). We used the small ones to hold DH's gift to his Scouts (an emergency kit for hiking--whistle, compass, flint in one, on a string), and got some to put in the Christmas boxes (to send overseas). We have them for decorations too.
Small gifts to put in to those Christmas boxes (hit Michael's and Target $1 aisles also---managed to fill 5 of those shoeboxes for less than $30). Puzzles, checkers games, etc.
Tiny 5" orange traffic cones and racing related decorations (for Pinewood Derby)
Decoration stuff for all sorts of events, like Easter, Christmas, Halloween, Blue & Gold Banquet, etc
Stuff for my daycamp:
pencils, pencil sharpeners, sharpies, markers, stickers, plastic boxes to hold all that stuff, yarn, poster board, Foil
hand soap, sanitizer, tissues (little packages for the leaders to carry)
Craft stuff for the "tot lot"---foam stickers and pieces, suncatchers, etc.
coloring books, sudoku books for the leaders
DS likes to go in and look at the toy stuff, but has now realized that most of the toys are cheap junk, and is learning to not buy just to buy, kwim?
ETA: the last couple years, after Christmas, I pop in to the same store. They always have a ton of wrapping paper and tags left, and sell them $1 for 4! I bought a ton of Disney branded stuff--Frozen, Mickey, Princesses, Donald, Goofy, etc.
I still have 2 rolls left from my massive stock up spree back in 2002 (the grocery store had wrapping paper, tags and bows on clearance for .05-.10 each---mid-January and they found cases of Christmas stuff in the warehouse--so sold it real cheap to get it out of the way! I spent about $30--DH was in a bit of shock with the amount of stuff I carried in! I donated a bunch of paper, tags and bows when DH's old company did an "adopt a family" event), plus I gave some to DS's pack the last few years, to wrap the Scout's "Santa" gift from the pack, and to the kids schools for the kids Christmas shopping events.