A 4gb SCSI hard drive, ready to mount on an A1000. The hard drive contains all of the necessary technical files for the development of:
The PCI standard (and samples of the technology - it's not Amiga specific, so no field collapse!)
The USB standard (ditto!)
xGA graphics (VGA/SVGA/WXUGA, etc.) chipsets and associated 3d GPU technology (also ditto!)
16-bit audio technology (also also ditto!)
OS 4.0
PPC technology (note: I rather don't give a damn about PPC, but it's 1985 and Intel doesn't quite have a foothold yet - oh and also, also also ditto as well!)
TCP/IP protocols (ibid!)
The source code for various web-browsers (same!)
Documents outlining the importance of VM and multi-user and networking as standard (whoa yeah the same!)
Source code for all of iD's popular FPS's that they've released the code for (STILL not Amiga related! ha! I win!)
...and
finally...
A CDXL or ANIM-5 with sound of the Deathbed Vigil as a warning.
I count all of this as "one thing" since it's all on a single hard-drive!

EDIT: Actually, you know what? The Amiga could read DOS formatted hard drives - let's make 'em MS-DOS volumes just to be sure.
That way I can bring as many as I want! I'd bring a second with a full blown copy of Openstep and another with Linux (and sources) for the C= engineers to pore over.