THE CREATIVITY and enterprise of legislators and lobbyists reaches its fullest flower in a lame-duck session. Some of its more malodorous blossoms include the following.

* Sweets for the kids. Last year, the Department of Agriculture proposed allowing high-sugar cereals in the WIC nutrition program for undernourished preg nant mothers, infants and children. Under criticism, the USDA retreated. That did not, however, deter Sen. Mark Andrews (R-N.D.) and Rep. Bob Traxler (D-Mich.), who persuaded the House-Senate conference committee on the agriculture appropriation to make high-sugar cereals and chocolate milk eligible for WIC distribution. Both, perhaps coincidentally, represent sugar-beet-growing constituencies. The only way to defeat this measure is for either the House or Senate to reject the bill reported from conference.

* The drug-patent bill. Today or tomorrow, the House may consider the bill sought by pharmaceutical manufacturers to extend patent protection for new drugs to compensate for marketing time lost during government regulatory review. The House bill, unfortunately, is too generous: it extends the patent monopoly by the time elapsed between the first tests done on human subjects and FDA approval. The Senate's is even more generous: it extends monopoly protection to drugs already produced. But that isn't necessary to achieve the bill's purported purpose of encouraging new research. The danger here is that if the House bill passes, something closer to the Senate bill will be reported out of conference. Congress would do better to wait until next year.

* Gas tax amendments. The gas tax increase is in danger of becoming amended into a mess. The trucking interests have already got the cap on the user tax on trucks reduced from $2,700 to $2,000 in the House committee bill, and $1,600 in the Senate committee bill. They've also got a provision in the latter allowing weights up to 105,000 pounds -- a vast increase over the 80,000 allowed now in most states.

There's more. Sen. Gordon Humphrey, who filibustered the bill Friday, may offer an amendment to repeal the law requiring withholding on interest and dividends. Passed just last summer, this provides much-needed revenue owed the government under law, and its repeal would benefit primarily high-income tax evaders. Another threatened amendment is one reimposing price controls on natural gas. Some consumers will have to pay more this year than last because local utilities made bad bargains. Perhaps they need relief. But price controls are a discredited policy that in the long run makes energy more expensive. It would be terrible if Congress suddenly moved backward on this issue.