As noted on the (hopefully not defunct) Fleer Sticker Blog, from 1960-62 Fleer include decal insert of a team logo with their baseball cards. There are differences between the years but the 1960 version measured about 2 1/4" x 3" looked like this:
The back of this one, which I swiped from eBay scans, was pasted into an old photo album but you can see the blue, no Dubble Bubble ad lettering that ID's it as a 1960 version:
Notice the trademark line below the text and above what I presume is a five digit product number? Well, some teams look like they licensed their logo while others did not. The reverse of the Dodgers decal (scan from Dave's Vintage Baseball Cards) has no such line:
The decals (OK, Emblems) were advertised on the wrapper for the 1960 Baseball Greats set on yet another nab from eBay):
I should probably show a Baseball greats card, eh? Well, from eBay (slight return):
Topps would not let this Fleer extra deter them and would respond by football card season. We'll take a peek at the football inserts from both Topps and Fleer next time out kids!