Used coffee grinds will attract worms like you put out a "GOLD RUSH" sign in your yard...please note that the worms do not eat your organic matter. As the organic matter (veggie peels, Kitchen scraps, grains, leaves, compost, lawn cuttings) decomposes, minute organisms feast on it to cause this "breakdown." The worms, in turn, feast on the minute ORGANISMS. So, the more breakdown of organic matter you have, the more smorgaasbord the worms will enjoy. Think of it as a free pass to the cafeteria!
P.S. When you see yucky, moldy looking stuff, REJOICE, because the worms will come!
P.S.S. The smaller you chop up those scraps before you throw them in, the faster they will break down in your compost...I sometimes put mine into a large plastic cookie jar (from Sam's/Costco) and leave it for a coupla weeks/months. It turns into a yucky slushy mess, and I just pull a trench straight down the center of my compost pile, pour it in and close the trench up, being careful not to let any scraps or odors escape. The exposed scraps and odors are what attracts unwanted wildlife and rodents who come foraging for them...
Hope this helps.
Linda, who is about to sift her latest haul of compost from last year's pile.