A Wyoming senator proposed this week that all retiring members of Congress be given $50,000 solid gold watches, appropriately engraved, as farewell remembrances.

Sen. Alan K. Simpson (R-Wyo.) was only kidding in his speech, but his point was that fancy watches would be cheaper than many of the legislative "gifts" that are being arranged by and for the departing.

Simpson was upset over Senate passage of a bill authorizing a $12 million federal courthouse of disputed need in Redding, Calif. House members called it "a going away gift" for defeated Rep. Harold T. (Bizz) Johnson (D-Calif.), outgoing chairman of the powerful House Public Works Committee.

As Congress prepares to adjourn, it is being asked to give a variety of legislative mementoes to the faithful and the fallen.

Some examples:

The dean of the Senate, Appropriations Chairman Warren G. Magnuson (D-Wash.), did all kinds of final favors for his state in the continuing resolution to tide over unfunded agencies, the final big measure to be handled this year.

Among them are money for a port development at Grays Harbor, Wash., a project not yet fully authorized by Congress, and about $11 million more for salvage work related to the Mount St. Helens volcano eruptions.

Magnuson also is trying to arrange federal purchase of a small island in Puget Sound, for use as a bird sanctuary. Earlier, Congress voted to name the National Institutes of Health clinic in Bethesda for Magnuson, long an NIH benefactor.

The same continuing appropriation includes provisions for severance pay -- up to three months' salary -- to Senate employes, presumably Democrats, who lose their jobs because of the changeover to Republican control next month. No estimate of the cost was available because no one knows how many Democratic heads will roll.

Another provision would assure continued revenue sharing money for the sheriffs of Louisiana. That state's sheriffs, thanks to Russell B. Long (D-La.), are the only ones in the nation who directly receive the federal funding.

Another retiree, Rep. William H. Harsha (R-Ohio), was memorialized by colleagues who voted to put his name on a lake a dam in Ohio. Harsha, in the same fraternal spirit, held up a House-Senate conference until it agreed to make his friend, Washington lawyer Ralph Becker, an honorary trustee of the John F. Kennedy Center for the Performing Arts.

Congress, meanwhile, finally found a way out of the ticklish dilemma over the Ditchley bells. The bells, replicas of those in Westminister Abbey, were given to this country as a bicentennial gift by England's Ditchley Foundation. But no one knew quite what to do with them.

The solution: Congress decided to hang them in the tower of the old Post Office building being renovated on Pennsylvania Avenue. It authorized $982,000 to do the job. Then it authorized another $800,000 to put in an elevator that will reach the roof.

Not quite in the memento category but no less memorable is the prestidigitation over a change of the boundaries of the District of Columbia.

In an appropriations bill that President Carter may veto because of its anti-busing provisions, Congress put language extending the federal district's boundaries by two miles.

That was so the Federal Communications Commission, which is supposed to stay in the District but wants to rent space in Rosslyn in suburban Virginia, could "legally" relocate.

A veto of the bill containing FCC money would throw the bogus boundaries issue back into Congress, where some senators are plotting an ambush.

The Environment and Public Works Committee, which has building-location authority, is upset because the FCC lease activity circumvents its powers and those of the General Services Administration. The committee may move to halt the FCC transfer to Rosslyn, staff sources indicated.